I have to say that I'm really happy to see My Web 2.0 launch (I got to see a beta demo a couple weeks ago). It's not immediately apparent, but it's personalized social search, using shared bookmarks between friends. I wrote about this back in December 2003 when I tried to come up with ways then-new social software sites could be useful. My second idea was to combine Friendster with Epinions so that you could search for reviews among your circle of friends, but I had it all backwards. Instead of turning Friendster into a search engine, Yahoo flipped that, by incorporating Yahoo 360 contacts into search.
My first thought when seeing this after thinking "cool, they built what I always wanted!" was that the bookmarklet posting interface does look a lot like the delicious posting interface, but I think these services serve different needs. I use delicious to bookmark all the neat things I find online, but Yahoo's search is more for reference things and epinions style bookmarks I want to save for later and share with friends. I guess though I've used delicious for a couple years now I still think of most material there as ephemeral, while I'm thinking My Web at Yahoo is better suited to permanent storage.
I'm changing my default browser search to Yahoo for a few days to see how it grows and becomes useful. It'll be interesting to see how the search gets better the more friends and saved pages get added. I'm already getting random other users mentioned above normal search results so that's a good sign. I can't wait to see what it's like in a few weeks when I do a random general search and find friend-approved links to exactly what I wanted instead of spammy search results or general information sites.
The other great thing I like about Yahoo's new search is that it attempts to circumvent one of my pet peeves: search engine spammers. Search engine gaming to get your URL high up in searches is a selfish act that degrades everyone else's experience and it's grown into a huge industry. Google has been gamed endlessly for years now to the point at which many general results have begun to suffer. I'm hopeful that if I limit my yahoo contacts to people I know and trust, no amount of search engine spamming in all the world by the SEO community will be able to muck up my results. In effect, this new search could kill an industry I thought would outlast the cockroaches, and that's a great thing.
Ross has a good summary of what this new push means for the worlds of social software and search. I'm curious to see what Google's next move will be. Hopefully they'll buy delicious and incorporate that.