It appears that Google is testing a new sitelinks format in the SERPs. I haven't seen this mentioned before in the blogosphere and it's the first time I've seen this new format so it's new to me.
Anyway, I'm only seeing the new format with branded/navigational queries. With the new sitelinks format, Google has rolled up paired listings along with multiple domain and subdomain listings for a brand into a new expanded sitelinks format.
Here's one for "WordStream"
And here's one for "Compete"
At first blush, I'm a little torn as to whether I like it or not. It's definitely better for user experience and someone running a navigational query. However, from a SERP management standpoint, rolling up my paired listings and subdomain listings into one big sitelinks section allows brand sqautters to rank higher on my branded queries since I'm no longer occupying as much space above the fold.
It will be interesting to see if they roll this out for non navigational queries as well, say for big brands in an informational query space.