Yahoo Photos will get a lot of Flickr features, and there are alot of other areas around Yahoo that will also be Flickrized where Flickrization would be good. Yahoo Photos and Flickr have different kinds of users with different needs, and will remain separate for the foreseeable future.?

Do I have to have a Yahoo ID to use Flickr?

No. In the future, you'll be able to log into Flickr using your Yahoo account, but you can continue logging on as before.

Will Terry Semel do the Developers Developers Developers shtick?

The fabulous Flickr API will continue to be open wide as all the outdoors, though we really gotta work on those commercial use licenses. Terry is as brilliant a businessman as Ballmer, but alas, does not dance. It messes up his hair.