I heard a slight squeaking noise underhood. It has gotten a little louder, and seems to be coming from the power steering area. I hear it mostly in gear, but it can be heard more faintly in neutral. I hear it when moving, but more faintly when stopped. I hear it whether the A/C is on or off. I popped the belt off to check the idler pulley-seems fine. I tried to feel for any pulleys that were loose, siezed, bearing wear, etc. The only thing I found is that the power steering pulley seems to have 'end play'. By that I mean that it slides in/out of the power steering pump about 1/4 inch. All other pulleys seem to have no movement. I can even see the belt walk on the fan pulley (presumably from the power steering pulley moving). Do I have to replace the power steering pump? or can I just replace the pulley?

 

Ive been noticing a squeal lately too. I haven't gone as far as you have investigating it yet.
It seems to be in the morning mostly. And goes away after a few minutes. I thought it might be the belt - couples with some rusty, moisture ridden pullies (read: Massachusetts weather). Time will tell -