They've been testing this publicly at askx.com for months. The new ask.com updates what they had at askx with skins. Everything else seems the same.
These aren't frames, though. It's done with CSS.
I'll repeat the same minor criticism I gave askx some time back - it's confusing that there is an "opening page" that is completely different from the interface once you have done a search. That is, upon initial entry, there's one big page with a search box. Once you've done a search, it splits in two, and now the search box is in the left-hand "frame". Why not just start out with the "frames" and make it consistent?
I particularly like the narrow/widen result options. Nothing new for ask, but it is presented much more clearly than before.