RE: Google Apps integrated with MS Dynamics CRM
There is no first-party integration between Google Apps and Dynamics CRM, though I know in the past some people have used Outlook's Google Apps Sync to make Outlook the front-end for both CRM and Google Apps.
I suspect if you can get Google Apps to post POP3 mail, you could use the Email Router to integrate mail between the two systems, though that is rather limited.
I believe there are some third-party integration systems out there, but I don't know how current they are, and I'm sure they're not nearly as integrated as Office 365 is with Dynamics CRM. As in, more than just email, also document creation and storage, Outlook Groups, OneNote, etc.
Frankly, that is one of my hard breaks when people ask me if they should use Dynamics CRM. If they're a committed Google shop, then likely not. SFDC is much better integrated to Google, and will cause less heartache to anyone implementing it, even if I think SFDC is by itself an inferior product.