Why would there be an ifconfig listing en2 with 169.254.x.x on OSX 10.6.8?

Web browsing was becoming very slow, after trying in two different places (home,starbucks). I was looking at ifconfig output and everything I found reasons for, lo0 gif0 stf0, except for one of the enX interfaces:

en2: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500

ether 0b:0b:0b:0b:0b:0b 
inet6 fe80::223:32ff:fec7:d2dc%en2 prefixlen 64 scopeid 0x5 
inet 169.254.193.122 netmask 0xffff0000 broadcast 169.254.255.255
media: autoselect (10baseT/UTP <full-duplex>)
status: active

I used sudo ifconfig en2 down, and the browsing immediately improved. I am wondering what this is/was?