Some have reported that using rfcomm instead of letting Maemo Mapper handle the connection may eliminate the problem. You can specify an rfcomm device (e.g. /dev/rfcomm5) in Maemo Mapper as of v0.2.4 and v1.0, so give it a shot.

For best results, go into root and use rfcomm bind; otherwise, an rfcomm connect is sufficient, but you'll have to do it every time you want to connect to the receiver.

I have never seen a hang in my limited testing with rfcomm-based connection, but then again, I also haven't seen a hang in the hours of continuous without rfcomm in the 2006 OS (I saw the hang a few times in the 2005 OS, but not as much as others have seen it).