YC was (and is continuing to be) very valuable for us. Sachin Rekhi has written up a good summary, which I broadly agree with: http://www.sachinrekhi.com/blog/2009/02/26/the-value-of-the-... -- and I would add to the list of benefits the massive network of the YC partners, who will happily make valuable intros.

Many other companies in our batch soon launched too, so we soon all ended up at pretty much the same stage.