Scarbones has pointed to something pretty cool: a clustered search interface to MSN Search released by Microsoft Research in Asia. I'm not sure how long it has been 'out there'...

"MSRA SRC Toolbar is a tool for searching web with the Search Result Clustering (SRC) technique, which is developed at Web Search and Mining Group in MSR, Asia. It on-the-fly clusters a certain search engine's search results into different groups, and provide meaningful and readable names for these groups. SRC changes the traditional representation of search results into a non-linear way, so as to facilitate user's browsing."

There's a web inteface and a toobar for download (IE only me thinks...):

--

Web interface:

Toolbar:

--

The query 'Alex Barnett' brought back some nice results. One of the groups returned was 'blogs' (amongst others) and had a 'comment,email' sub-group under that (also includeed trackbacks to other posts). 

Given this is a research project right now, with some user feedback (hey, I'd like to subscribe to the results in RSS!), more dev and UI work (not much though) and further improvemens to underlying the MSN search algorithms could turn SRC for MSN Search into something really juicy.  I hope the MSN team are able to do something with this and provide MSN APIs / SDKs (btw, SRCs results for this query, nice!) for others to play with.