Hopefully they come together. Obviously, even if Marbury becomes Rajon Rondo on the defensive end, it's still not going to be ideal to have two sub 6-2 players on the court together. Given that's the case, if they are to play together come playoff time, they're really going to have to make teams pay offensively, because inevitably there will be times that other teams will abuse either House or Allen with a taller player.
As someone noted above, I kind of like Marbury guarding the PG with House on the SG better than the reverse. Though Marbury may have an inch or so on House, House is a little thicker, letting him body up bigger two-guards. Plus, while Mo Williams arguably abused Steph a little last night on his way to 26 points, Mo also had the worst +/- on the Cavs last night, perhaps suggesting that his efforts to take advantage of Steph took the Cavs out of their usual offensive sets.