I've come across a problem when moving a mailbox from a 2007 server (Mailbox, CAS, HT) in one site to an Exchange 2010 server in in a different site (MB, HT,CAS).
Outlook 2010 clients update aytomatically (talk about smooth, nice work Microsoft!)
Outlook 2007 clients (With or without Outlook Anywhere enabled) remain "Disconnected" for about 2 hours, when it suddenly starts working.
I can reproduce this behaviour consistently. Looking around I can't find any indication of why this may be, perhaps the Information Store caches something for a period of time and since Outlook 2K10 connects to the CAS role it's not effected? With diagnostic logging in Outlook 2007 enabled there's hardly anything logged (nothing related to MAPI etc anyway).