Really? If you base hiring a developer on a huge portfolio, you may be missing some of the most capable people/firms.
Why? Most schools, government, University, non-profit, and large/branded sites do not want/allow "Site designed by soandso.com". As a matter of fact the largest jobs we were ever involved with do not want anyone knowing you developed their sites and always have that stipulated.
There are many portfolios out there from other designers/developers pointing to sites we "redesigned" or "completely" changed for clients. It's funny to watch them update their image/snapshot of a site that has nothing to do with what they had originally done for the client.
Also, now days the only work I ever do is for other developers for their own projects or for their clients and they take the credit (which is fine by me)...hehe
My point is, portfolios are like testimonials...don't put to much weight or rely upon them to heavily ;)
[edited by: The_Contractor at 10:15 pm (utc) on Feb. 12, 2007]