This looks interesting, but I don't think it's really useful.

seobook.com/google-beta-testin ...

The related phrases could be useful since they appear to be summarising each of the results. In the example given in that post, I guess you could therefore (perhaps rightly or wrongly) assume that the first result contains information relating to link building software whereas the second result doesn't. If the related phrases are calculated properly, this could help the searcher establish which result is more relevant to their needs.

It seems like it might confuse some average users, while it could be beneficial for power users and perhaps those doing keyword research.

Personally, I really like this. Maybe you don't know the right word for a query, but by surfing around on related queries you'd be able to find the right term so that you can modify or refine your search.

Does that mean we can count on a full roll out sometime soon Matt? :)