I was previously using 4Smartphone to provide my hosted exchange server but read an article about Microsoft’s oferring: Microsoft Office 365, so thought i best take a look!
I have been trialling the product for just under a month and have decided to purchase a license! In short- Office365 encompasses a lot more than just hosted exchange (lync/ocs, sharepoint etc) and the cost is less than 4Smartphone (£4/month vs. $11.95/month).
The mailbox migration was really straightforward: I simply exported a .pst file using Outlook 2010 (connected to 4Smartphone) then imported the same .pst file in Outlook 2010 whilst connected to Office365.
Lync (what used to be OCS) seems to work well and allows federation with other companies, hosted or otherwise.
Give it a try!