A WebmasterWorld thread has SEOs noticing that Bing has increased the number of "Sitelinks" shown for a search result.
They can now show 8 sitelinks for a single search result.
Here is a picture:
I am not sure how "new" this is, but the folks at WebmasterWorld seem like there was an increase recently.
One SEO even said they may do even more:
Now Bing is showing not just one but two two sets of site lineks (one block of 8 and one of 4) on the same page of the SERPS.
Forum discussion at WebmasterWorld.