Does anyone know if there are plans for a "Last XX Posts" hack for v6x of UBB? this is one of the biggest requests from my users of my boards.

Not sure exactly what you mean, but the most recent posts made by an individual user is accessable through his/her profile:

https://www.ubbdev.com/ubbcgi/ultimatebb.cgi?ubb=recent_user_posts&u=00000973

I am refering to the "Last 30 posts" hack that is out for the v5x of UBB. I know the way that UBB does the new system (v6x) this might not be easy (if at all possible) but just thought I'd see if any one was going to try.

thats called active topics i believe