Briefly: Re-Locking Your iPhone
iPhone hacker extraordinaire, Mrs Erica Sadun has posted a rudimentary guide to re-locking your iPhone. This guide was created is in response to recent news that the next firmware update may leave your iPhone irreparable if it has been unlocked. The guide currently requires quite a bit of command-line work which may deter quite a few people. Erica has stated that the instructions will be updated over time to incorporate inaccuracies and other various tweaks.
Simply restoring your iPhone will not currently re-lock your iPhone. Once you've re-locked your iPhone, 3rd-party applications can still be installed. An alternate re-locking guide can be found at iPhone Go Boom.
Apple is expected to release an iPhone software update any day now to add such features as the iTunes Wi-Fi Music store and other rumored additions.

Delicious
Reddit
Technorati





Hopefully that will help. If you're not familiar with terminal, I'd suggest waiting until the instructions are solid