Confused on wether to upgrade

I tried searching forum and not finding right post I guess....Have a 3gs phone that has not been upgraded to 3.1 as of yet due to being Jailbroke. Phone is working fine with no battery issues and using PDAnet flawlessly. I would like to have the MMS feature but dont want to lose my PDAnet. Is there a Jailbreak out yet for the 3.1 and 3GS...Seems like I used Purpleriain or something last time to jailbreak and work without a glitch...

Anyways sorry if the question already been discussed but would rather not upgrade if PDAnet not going to work or unable to jailbreak 3.1 using a 3gs phone