What does mc_mobile_tunnel represent in a crash log?

A coworker handed me an iPhone that crashed in the middle of our app running. The crash report credits the crash to mc_mobile_tunnel rather than our application.

Process:         mc_mobile_tunnel [7322]
Path:            /usr/libexec/mc_mobile_tunnel
Identifier:      mc_mobile_tunnel
Version:         ??? (???)
Code Type:       ARM (Native)
Parent Process:  launchd [1]

Date/Time:       2011-03-24 13:53:15.294 -0700
OS Version:      iPhone OS 3.1.3 (7E18)
Report Version:  104

Exception Type:  EXC_CRASH (SIGABRT)
Exception Codes: 0x00000000, 0x00000000
Crashed Thread:  0

Thread 0 Crashed:
0   libSystem.B.dylib               0x304a0b2c 0x30410000 + 592684
1   libSystem.B.dylib               0x304a0b1a 0x30410000 + 592666
2   libSystem.B.dylib               0x304a0b0e 0x30410000 + 592654
3   libSystem.B.dylib               0x304b7e34 0x30410000 + 687668
4   libstdc++.6.dylib               0x34162390 0x340fc000 + 418704
5   libobjc.A.dylib                 0x329c0898 0x329b8000 + 34968
6   libstdc++.6.dylib               0x3415fa84 0x340fc000 + 408196
7   libstdc++.6.dylib               0x3415fafc 0x340fc000 + 408316
8   libstdc++.6.dylib               0x3415fc24 0x340fc000 + 408612
9   libobjc.A.dylib                 0x329bee54 0x329b8000 + 28244
10  CoreFoundation                  0x3241eb2c 0x323f8000 + 158508
11  CoreFoundation                  0x3241eacc 0x323f8000 + 158412
12  Foundation                      0x308e1220 0x3089c000 + 283168
13  mc_mobile_tunnel                0x00002884 0x1000 + 6276
14  mc_mobile_tunnel                0x00002030 0x1000 + 4144

What is mc_mobile_tunnel, and why is it taking out my application?

I think symbolizing your crash-log would give you more insight as where exactly the problem might be. See this post for how to do it: How to interpret a crashlog with no references to a specific class

However you need the dSYM Bundle which you get when you build the application (it's right next to your App in the build folder).

Example:

Symbolized Crashlog http://k.minus.com/jk4X2obwZMI7j.png

Another side remark there is a free service, which I consider to be a must-have, called Testflight which is really great for beta testing as it stores the crash logs online and can also do the symbolization for you.