Among other things, users will be able to access, edit, and share Office 365 content from Salesforce/Salesforce1, and connect Salesforce data to Excel. Also, a new Salesforce Outook app will be developed.
Salesforce also says it plans to extend Salesforce1, which has a strong mobile focus, to Windows and Windows Phone. General availability is due in 2015.
Bloomberg reported this morning Salesforce's apps are set to run on Azure, and that a data integration deal is being discussed. The latter has been corroborated by the PR, but the former hasn't as of yet. A CC (starts at 4:45PM ET) should provide more details.
Update (6:00PM): Salesforce shares are up 1.8% AH.