This jailbreak supports 2g, 3g, 3gs, and iPod touch 2 on 3.0. Key features:

1) Stable jailbreak tested by dev-team
2) Icy + Cydia problem solved (we think).
3) Ultrasn0w tested and working on 3gs
4) Proper kernel patches which will enable logome (after it’s updated for 3.0).
5) Mobile Substrate + Winterboard now working on 3gs.

Again, for download links and redsn0w installation guide, go here.

Note: If you used purplera1n RC2 or newer, you do not need to redo  your jailbreak. You will be unable to use logome in the future, but that should be the only downside. If you used purplera1n RC1 or older, you should redo your jailbreak. I believe you can run redsn0w right over the top of it.