I just came across a blog which believes that the new look for Google Docs and Spreadsheets (or rather Google Office) could be an indication for a new UI for GMail. The author even includes a mock up of how such a look for GMail could turn out to be.
From this mock-up it is easy to see that the new look is much more aesthetically pleasing than the current UI, and it retains the simplicity and ease of use that made us fall in love with GMail in the first place.
However, this might end up becoming more that just a new look for Google Office and GMail, it could easily turn into a consistent interface across all Google Services, which so far has been rather fragmented. This interface could easily blend in with services such as Google Reader and Google Calendar, as well as others like Google Groups and Google Photos (Web Albums).
A unified interface would increase usability since, once a user becomes familiar with any one service, he or she could easily figure out how to use the other ones, thus increasing adoption. Google's competitors, namely Microsoft and Yahoo! has so far been unable to implement a consistent interface across their web services, and this could put Google another step ahead of them.