The Inq says that Intel has Yonah processors listed at 2.50GHz. The Yonah is a dual-core Pentium M.
First, Intel has Yonahs listed as X20/30/40 and 50 at unlisted clocks. They are unlisted because Intel is not sure how well they are going to bin out yet. The target is 2.5GHz, but one speed bump up or down is entirely possible now, so if there is a 2.33GHz or 2.67GHz part at launch, don't be all that shocked. This would put the X50 at 2.5GHz optimally, X40 at 2.33, X30 at 2.17 and the lowly X20 at a mere 2.0GHz. In case you hadn't guessed by the numbers, the bus is 667MHz.