Wow, JRebel... always wanted to try that but I guess the pain of waiting
on the restarting app server just isn't big enough yet. To the error you
are reading: is this from the hosted mode? I suspect there might be
something going on with the RPC policy files.
I read that there are indeed some problems with GWT and JRebel [1]...
does this happen only with SL projects?
[1] http://www.zeroturnaround.com/forum/topic.php?id=470