To Eric's recent post about how he as a Microsoft Student Ambassador is collaborating with his Apple Campus Rep counterpart, I've heard a lot of examples of this, as part of another aspect of my job, managing the US Student Ambassador program.
Personally I love the idea - members of both programs can learn a lot from each other.
Although the focus of the two students on a campus may be different - Microsoft Student Ambassadors are generally Computer Science or related majors and talk about things like the .NET development platform - WHAT they do is often similar enough to get a lot out of sharing of ideas, at least. Events, student clubs, install fests, and so on.
Plus some joint events and activities could be a lot of fun for all the students involved.
So Apple - if you are reading this blog (and I read your student blog <g>), and are interested in connecting our Ambassadors with your Campus Reps here in the US, drop me a note! kevinbri at microsoft dot com, anytime.