It’s called Alpha and I couldn’t get it do much.
From Digital Inspiration:
Unlike Google Custom Search engine which is closely tied to Google Web Search, Yahoo! Alpha shows search results from various Yahoo! or third-party services on the same page.
The services currently available are Yahoo! Web search, Wikipedia, Flickr, YouTube but you can build your own search modules as long as they provide search results are available in the form of RSS feeds.
Amit Agarwal is also right to point out that Alpha is really sort of like a Netvibes, PageFlakes, or Google Personalized Home Page where every widget is a search widget.
In addition to…well…not working for me…it also doesn’t have the functionality to let the user add a whole bunch of sites at once and it forces the user pass a CAPTCHA for each URL entered- that’s annoying. It would take a looooooooong time to replicate my Google CSEs (example) in Yahoo! Alpha. Also, it can’t be embedded in a Web page the way Google CSEs can.
Maybe when Alpha is a little further along as a Beta I’ll get excited about it. For now…not so much.