Sure, I can do that. But first I need to start off with this disclaimer: purplera1n is considered by geohot (George Hotz), to be in beta. After messing around with my JB 3GS, I consider purplera1n to be more along the lines of alpha.
Things are very glitchy... and when I say very, I mean very. Some apps seem to cause the springboard to crash and only work in safe mode until I remove them. There seems to be no rhyme nor reason for this either. So far today I have JB my 3GS 3 times. During one of the times, iRealSMS was working fine. This time, it crashes my springboard so that it only works in safe mode.
So right now, the only real JB apps I have installed are SBSettings, iBlacklist, Cydia and Icy. I need to leave for work in about 30 mins, so I don't want to mess around with more apps right now -- don't have time for another restore.
The purplera1n jailbreak is actually pathetically simple. You just download the app from
http://purplera1n.com/ by clicking on the windows logo. I had iTunes running, then just launched the program and clicked the "make it ra1n" button...
The button will change to something like "setting to recovery mode". Kinda nice how this does it for you... no more pushing buttons.
After a few seconds, you'll see geohots pic on your iphone. After a few more seconds, it'll say "all done, wait for your phone to reboot". At this point, I just closed out of the purplera1n app. Took maybe another 15 seconds for my phone to reboot.
When my phone booted back up, there was an icon on it (syncing movies back to my phone, so can't check). I think it was called something like "Freeze". When you launch that, you have one option, "Install Cydia". That button will download and install Cydia for you, so if you have wifi available, you might want to connect as it'll go faster.
Once Cydia is installed, I launched it and installed the RipDev repository. Once that repo is installed, you can install Icy.
Hope this is what you're looking for.