How should this seemingly mysterious crash report from 4.1 be interpreted?

I'm getting a lot of complaints from people using 4.1 about my app crashing. I was finally able to track down a device with 4.1 and get the crash logs from it (by the way, is there a way that I can use the simulator with 4.1?) and I'm not sure how I can interpret them. I'm thinking the culprit may be AdWhirl, but I can't confirm this because the crash log doesn't mention it. Here's the log:

Incident Identifier: D63B6947-B553-4816-BFF3-451105DF6AC1
CrashReporter Key:   e48b7e0079de90291849ebebfa2c4d2b3533593c
Hardware Model:      iPhone3,1
Process:         TruxMapFree [795]
Path:            /var/mobile/Applications/51E80AC4-C5FF-4D3B-95CE-A2F5A96FBF85/TruxMapFree.app/TruxMapFree
Identifier:      TruxMapFree
Version:         ??? (???)
Code Type:       ARM (Native)
Parent Process:  launchd [1]

Date/Time:       2011-02-01 11:44:57.883 -0800
OS Version:      iPhone OS 4.1 (8B117)
Report Version:  104

Exception Type:  EXC_BAD_ACCESS (SIGBUS)
Exception Codes: KERN_PROTECTION_FAILURE at 0x00000000
Crashed Thread:  0

Thread 0 Crashed:
0   TruxMapFree                   0x0003d196 0x1000 + 246166
1   TruxMapFree                   0x000463ae 0x1000 + 283566
2   TruxMapFree                   0x000468ca 0x1000 + 284874
3   CoreFoundation                0x0003e2e4 -[NSObject(NSObject) performSelector:withObject:] + 16
4   Foundation                    0x0002081e __NSThreadPerformPerform + 262
5   CoreFoundation                0x00055f1e __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 6
6   CoreFoundation                0x00027ba0 __CFRunLoopDoSources0 + 376
7   CoreFoundation                0x00027444 __CFRunLoopRun + 224
8   CoreFoundation                0x00027270 CFRunLoopRunSpecific + 224
9   CoreFoundation                0x00027178 CFRunLoopRunInMode + 52
10  GraphicsServices              0x000045ec GSEventRunModal + 108
11  GraphicsServices              0x00004698 GSEventRun + 56
12  UIKit                         0x0000411c -[UIApplication _run] + 396
13  UIKit                         0x00002128 UIApplicationMain + 664
14  TruxMapFree                   0x00003a4a 0x1000 + 10826
15  TruxMapFree                   0x00003a14 0x1000 + 10772

Thread 1:
0   libSystem.B.dylib             0x0002d330 kevent + 24
1   libSystem.B.dylib             0x000d6b6c _dispatch_mgr_invoke + 88
2   libSystem.B.dylib             0x000d65bc _dispatch_queue_invoke + 96
3   libSystem.B.dylib             0x000d675c _dispatch_worker_thread2 + 120
4   libSystem.B.dylib             0x0007a67a _pthread_wqthread + 258
5   libSystem.B.dylib             0x00073190 start_wqthread + 0

Thread 2:
0   libSystem.B.dylib             0x00000c98 mach_msg_trap + 20
1   libSystem.B.dylib             0x00002d64 mach_msg + 44
2   CoreFoundation                0x00027c38 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                0x000274c2 __CFRunLoopRun + 350
4   CoreFoundation                0x00027270 CFRunLoopRunSpecific + 224
5   CoreFoundation                0x00027178 CFRunLoopRunInMode + 52
6   WebCore                       0x000024e2 RunWebThread(void*) + 362
7   libSystem.B.dylib             0x0007a27e _pthread_start + 242
8   libSystem.B.dylib             0x0006f2a8 thread_start + 0

Thread 3:
0   libSystem.B.dylib             0x00000c98 mach_msg_trap + 20
1   libSystem.B.dylib             0x00002d64 mach_msg + 44
2   CoreFoundation                0x00027c38 __CFRunLoopServiceMachPort + 88
3   CoreFoundation                0x000274c2 __CFRunLoopRun + 350
4   CoreFoundation                0x00027270 CFRunLoopRunSpecific + 224
5   CoreFoundation                0x00027178 CFRunLoopRunInMode + 52
6   Foundation                    0x0002d686 +[NSURLConnection(NSURLConnectionReallyInternal) _resourceLoadLoop:] + 206
7   Foundation                    0x0000b222 -[NSThread main] + 38
8   Foundation                    0x000042d6 __NSThread__main__ + 966
9   libSystem.B.dylib             0x0007a27e _pthread_start + 242
10  libSystem.B.dylib             0x0006f2a8 thread_start + 0

Thread 4:
0   libSystem.B.dylib             0x00025060 select$DARWIN_EXTSN + 20
1   CoreFoundation                0x0005edfc __CFSocketManager + 540
2   libSystem.B.dylib             0x0007a27e _pthread_start + 242
3   libSystem.B.dylib             0x0006f2a8 thread_start + 0

Thread 5:
0   libSystem.B.dylib             0x0007b19c __workq_kernreturn + 8
1   libSystem.B.dylib             0x0007a790 _pthread_wqthread + 536
2   libSystem.B.dylib             0x00073190 start_wqthread + 0

Thread 6:
0   libSystem.B.dylib             0x0007b19c __workq_kernreturn + 8
1   libSystem.B.dylib             0x0007a790 _pthread_wqthread + 536
2   libSystem.B.dylib             0x00073190 start_wqthread + 0

Thread 7:
0   libSystem.B.dylib             0x0007b19c __workq_kernreturn + 8
1   libSystem.B.dylib             0x0007a790 _pthread_wqthread + 536
2   libSystem.B.dylib             0x00073190 start_wqthread + 0

Thread 8:
0   Foundation                    0x000eb1ec DYLD-STUB$$CFURLRequestGetURL + 0
1   Foundation                    0x0002dab2 -[NSURLRequest URL] + 18
2   Foundation                    0x0002d990 createCFRequest + 144
3   Foundation                    0x000aed5e +[NSURLConnection sendSynchronousRequest:returningResponse:error:] + 30
4   AppSupport                    0x00015c5e downloadDictionary + 122
5   AppSupport                    0x00015d5c -[PEPServiceConfiguration _updateDefaults:] + 76
6   Foundation                    0x0000b222 -[NSThread main] + 38
7   Foundation                    0x000042d6 __NSThread__main__ + 966
8   libSystem.B.dylib             0x0007a27e _pthread_start + 242
9   libSystem.B.dylib             0x0006f2a8 thread_start + 0

Thread 0 crashed with ARM Thread State:
    r0: 0x004ade00    r1: 0x3303ae3b      r2: 0x00000000      r3: 0x00000000
    r4: 0x004aef20    r5: 0x0017dd8d      r6: 0x00000000      r7: 0x2fffea2c
    r8: 0x004ad560    r9: 0x2fffe8e4     r10: 0x0017e45f     r11: 0x0017e453
    ip: 0x00000000    sp: 0x2fffea14      lr: 0x0003d181      pc: 0x0003d196
  cpsr: 0x600f0030

Binary Images:
........

Any advice is greatly appreciated!

I have no experience with this, but I'll have a crack anyway because it's interesting :-)

My guess would be that thread 8 or more likely thread 3 (mach_msg_trap?) triggered some call back to the app which then tried to perform a selector on a nil object.

Just a wild guess :-)