I am using my iTouch as iTunes remote. Depending on what you do, it can be adequate. But compared to a SqueezeBox or SoundBridge, it is pretty limited; 1) You cannot "add to the playlist" (anything you touch starts playing right away, replacing what was playing before); 2) Fonts are very big and it is impossible to distinguish between anything that shares the first 15 letters or so (no multi-lines or scrolling).
If you do not have 1000+ CDs or listening mostly/only to rock or popular music (not problems with a 100 entries starting with "Mozart: Symphony no" (oops, no more space!), it can be quite good; just don't buy iTouch or iPhone for that purpose; make sure it is just a perk on top of your other needs.
But if you do have an iPhone already or an iTouch, then using an AirPort is actually is very convenient solution.
E = MC2 = ((2M80 + VP180 + 4QS8)/(EP800 + EP500))^(ADA1500 x D2v)