With 10.6, I routinely had two accounts logged into the Mac while I was working - my personal and my work account. I switched between them as needed and this worked fine. For example, if I had an IM client running under the work user and switched to my personal user and then back again to the work user, everything was ok. The work user's IM client stayed connected the whole time.
With 10.7, it looks like switching to another account renders the network connection inactive for the account that is no longer in use. When I switch back to the work account now, the IM client has to reconnect and the VPN attempts to reconnect.
Is this new behavior documented somewhere and is it configurable?