Unless you've been hiding in a cave for the last few days, you've no doubt heard about Windows Mobile 6. I've been running WM6 for about a year now and am absolutely in love with it.
This great new release includes support for advanced Exchange 2007 features like mailbox Search, Out-of-office, HTML email (so when you reply to a thread it doesn't all revert to plain text!!!), end storage card encryption, as well as full Windows Live support.
Read all about it over at Jason Langridge's blog.