I went rummaging around the GoogleTV G+ group, and it seems there are a few new-ish features that show that things haven't completely stagnated on GTV.

. Prime Time Quick Guide (an overlay search thing that seems to me to be more annoying than useful)
. YouTube "send to your TV"
. Voice Search (assuming you've got a microphone somewhere; my GTV doesn't have one)
. Assorted integration of the Google Play store for movies and TV shows

And I guess there are some semi-important new 3rd-party apps. Notably, Amazon Instant Video is now supported. Sirius XM announced something, but it's not available yet. If you want to work with the movie industry's "Ultraviolet" standard, you can use the Flixster app. So... that's certainly not nothing.

This all looks, at least from the outside, like Google has a modest team that's steadily turning the crank. In terms of long-term strategery (sic), I wouldn't be surprised if Miracast is a big part of it, trying to leverage the success of Android on phones/tablets. Not that GTV supports Miracast. Yet.