I have to agree with other posts. I expect to see Swordmage in the equivalent of the Complete Arcane Power (4X) released in the 2008 schedule. I do not think they would have given the thumbs up to an entire trilogy based on the Swordmage, to be released in the 2008 product line) if it wasn't going to see the light of day until some time in 2009+. However, the timing might be slightly off and it be seen very early in 2009, but I wouldn't expect a full year delay from PHB1 to seeing the Swrodmage.
Just as a side note, I believe they are going to be intent on taking systems and concepts people liked most from 3.5X and translating them in theory over to 4X. The swordmage is basically a translation of all the melee/spellslinger combinations attempted over the years (duskblade, hexblade, etc.). I believe they will do the same for other power sources that were received well. Thus, I am putting bets on PHB2 = Psionic, Incarnum and either Shadow or Binding power sources.
Following this model, with a 3 New Core each year (PH, DMG, MM) and 3 corresponding splatbooks, they have a solid 6 "heavy book" core product list for the year which can then be supplimented by all of the other product lines (adventures, campaign world material, novels, map tiles, minis, etc.)