I was able to log in to the MIT SECURE wireless network as "jruser", on MacOS 10.6.4. The initial connection attempt successfully associated but failed to get DHCP. Subsequent connection attempts worked just fine, and I received a valid IP.
kadmin: getprinc jruser
Principal: jruser@ATHENA.MIT.EDU
Expiration date: [never]
Last password change: Wed Sep 15 09:17:15 EDT 2010
Password expiration date: [none]
Maximum ticket life: 0 days 21:15:00
Maximum renewable life: 7 days 00:00:00
Last modified: Wed Sep 15 09:17:15 EDT 2010 (jdreed/admin@ATHENA.MIT.EDU)
Last successful authentication: [never]
Last failed authentication: [never]
Failed password attempts: 0
Number of keys: 1
Key: vno 5, Triple DES cbc mode with HMAC/sha1, no salt
MKey: vno 0
Attributes:
Policy: default