[imp] concurrent session support

[Kevin Konowalec]

Has anyone successfully implemented a multi-server horde setup using  
mysql sessions?  I've just upgraded to the latest version of imp,  
which I was hoping would solve the "requested message not found"  
problem that was attributed to concurrent sessions with sql backends  
that may not support locking.  Unfortunately it doesn't.  Not being a  
mySQL DBA I have no idea how to check if my installation does or  
doesn't support locking.  All I know is that I need to fix this  
problem because a LOT of users are complaining about it.  Can anyone  
share how they solved/avoided this problem?

I know some places use memcached as their common session backend.   
Can anyone share any insight on how they set that up and how well it  
works in a multi-front-end environment?