I don't see any positive responses from a search of Transmission forums so i wouldn't count on maemo Transmission port getting it anytime soon.

http://forum.transmissionbt.com/view...er=asc&start=0
http://forum.transmissionbt.com/viewtopic.php?t=1245

If any linux developer wants to add such support they can either build off my source or upstream svn. I would think best solution would be system level though, but then i'm not familiar with these ip blockers.