This is pretty much exactly what Rapportive had just released except this has some added functionality. They imitated it very quickly unless they had plans to do this all along..
Xobni also had indicated it wanted to get into Google Apps and Gmail at some point in the near future. I wonder if this is the new model for building services on top of Gmail..
I haven't tried this, but http://sites.google.com/site/oauthgoog/Home/oauthimap doesn't at all look private to me. In fact, when I found that, I was very happy to see this ingenious combination of SASL and OAuth.
You certainly can't run it in conjunction - i.e. gmail in one tab and google apps in the other - it only handles one acct (unlike Rapportive). I didn't try just a google apps account.
Xobni also had indicated it wanted to get into Google Apps and Gmail at some point in the near future. I wonder if this is the new model for building services on top of Gmail..