Facebook appears to be testing a "locked navigation bar: so that users can scroll further into lifestreams. You still have to click to 'see older posts'. In the screenshot below, you can see how the page is scrolling under a locked bar as half of the 'news' item is missing.
Realtime Notifications spotted appearing in the top left corner. The unit is approximately three ad spots tall, updates in real-time, and infinitely scrolls on mouseover through all notications.
New Stories from 'Verbing' Buttons
One other interesting characteristic of this real-time notifications feature is that new types of Facebook 'stories' were appearing within the Ui. These were in line with Facebook's tendency of 'verbing the web' - for instance, the new stories created sentences out of the 'attending' event feature, where you can click 'I'm attending' - the end result is a story such as "Michael is now friends with Lisa after attending the Summer Gala event".
Response to Google+
I think it would be premature to say that this is in direct response to Google+ but it is worth noting that the black "Google+ Bar" has been getting a fair amount positive and negative attention. On the negative side, users have felt that the +Bar has been imposed upon them, whilst on the positive side some users have liked it so much that they have expressed the wish to lock the Google+ Bar in place.