In general, both the new Nexus 7 and Android 4.3 seem to be decent improvements over the previous versions, but nothing groundbreaking was announced.
The Nexus 7 in particular is just enough of an improvement that i'm tempted to get one, but not so much of an improvement that i can really justify it. Perhaps if i can "con" Avalyn into buying my old Nexus 7 for $50-$100 and thus subsidizing the purchase of the new one ;)
They also announced "Chromecast", a dongle that you plug into an HDMI port in your TV (oops, i think i've filled up all of mine =P) and lets you stream content to your tv via WiFi. Some content. Like YouTube and Netflix and Pandora and the stock music player. I think that's all the sources they listed so far. Oh, and you can do photo slideshows. Yay. So other than the ability to stream music from your phone i'm not sure why you'd get this instead of Roku. Perhaps because it's only $35? What do Rokus go for these days?
Anyways, that was most of the stuff that i found interesting, though it's always possible i missed something significant.
Source for most of my information:
Cross-posted from G+