Gmail interface changed 7/01/09

I noticed some changes in the Gmail interface today and I'm not sure what to think of it yet. I used to change my site all the time; functionality, design... everything. I mean I just changed it recently--albeit a minor CSS change (went from a white background to a black one if you haven't noticed!)--but the functionality has stayed the same. Changes like this new Gmail change makes me realize that when people use a site as often as one might use the Gmail interface, they're used to a certain way of navigating... changing that is not necessarily good!