Nothing has really changed since Apple updated firmware 3.0 to 3.0.1 except for an SMS exploit patch. If you have a jailbroken iPhone, read Updating to Firmware 3.0.1 (Why you should wait) before proceeding. Therefore, nothing really changes with the jailbreaking and unlocking process.

The quickest way is to use redsn0w. The tutorial is up to date for the most part. The only difference you will notice is that even after you update to 3.0.1 through iTunes, you will still select firmware 3.0 in redsn0w to jailbreak and subsequently unlock your iPhone.
3 Easy Steps (A Quick Reference)
1. Update to 3.0.1 through iTunes
2. Select firmware 3.0 in redsn0w to Jailbreak and Unlock
3. Enjoy
[...] you don’t want to wait, check out How to Jailbreak and Unlock 3.0.1 Share and [...]
