Bloomberg claims that Microsoft and Salesforce are "close to an agreement" allowing Azure customers to use Salesforce's CRM programs. This possible deal sounds like it could be similar to the one just inked between Microsoft and SAP to bring a number of SAP's applications to Azure.
As part of the terms of the SAP deal, the two companies also announced they were more tightly integrating SAP applications with Microsoft's business-intelligence and Office/Office 365 wares. Bloomberg's report also mentions the possibility of Salesforce and Microsoft agreeing to some kind of Office integration.
Salesforce has been one of Microsoft's biggest PaaS competitors, not to mention its No. 1 CRM rival.
Microsoft's Dynamics CRM Online service is not (yet) hosted on Windows Azure, but users can run Dynamics CRM in a virtual machine on Azure for testing purposes. I'm not sure whether Microsoft allows Dynamics CRM to run in a virtual machine for production purposes. It isn't on the list of Microsoft-certified Azure apps. (I have a question in to Microsoft to be sure.)
Update 1: A Microsoft spokesperson said Microsoft Dynamics CRM can be run in a virtual machine on Azure in production.
I asked Microsoft and Salesforce.com officials for comment on the Bloomberg report on the possible Microsoft-Salesforce deal. A Salesforce spokesperson said the company "does not comment on rumors and speculation." No word back from Microsoft so far.