Exalead the relatively new clustering search engine from France which I give my first impression last fall, was not supposed to be online at this time.
I received a email from the CEO Mr. Bourdoncle (a old AltaVista member) just after my post and I don't have anytime to release and test back the real thing about this since today. The launch was a leak and they got to let in online even after a they goofed on the parameters at midnight before indexing. That's why the number of pages indexed was at 300k at the place of the 500k promised.
But now the index is now at 1 billion page and the overall results in clustering and in SERP's are by far better. I got time today to compare Exalead with Clusty and I was amazingly surprise! It is the better clustering engine I seen from far. Also in the SERPS I discover a half a dozen results on me I never saw anywhere else (normally if I can saw 2 or 3 is very good on new engine). For a newbie like that it's promise well.
They will be some new things coming out soon with the Exalead Desktop (here some beta screen shots) in March and the Blog and RSS indexing. Also the meta-data of most multimedia files, archive and zip files may be come out soon with a index of 2 billion pages!
BTW: Don't forget to explore all the functionnalities of this search engine. Watch out GYM.