Edit: and for all intents and purposes, the GK104's ARE their flagship right now (as they've stated). I stopped holding my breath for GK110
Edit2: I can't find the press release, but here was a quote from someone on Hardforum:
Edit3: my guess is this august-november will be the GTX 660 in time for the holidays
The GK110 only recently taped out, so its not coming out any time soon. Huang stated at the press conference that it would not be released in a GeForce version until Q1 2013, because
1) Its not close to being ready yet
2) They are releasing it as a tesla first
So 680/690 will be the best cards until then, unless they do a re-spin of the GK104 or something.