I recently had the clutch replaced in my 2008 Subaru Outback. About 2 weeks afterward, I hear a squeaky noise when the clutch is disengaged. What could be causing that?
Definitely sounds related to your throwout bearing, I would take it back to whoever you had replace it.
You could either need a new throwout bearing (or perhaps it wasn't installed correctly), or there could be an issue with your master/slave or pedal, causing the clutch to not quite fully disengage and leading to the throwout bearing rubbing.
If the noise happens when the clutch pedal is all the way out (foot off the pedal) and goes away when you press the clutch pedal, even relatively lightly (not enough to move the pedal any more than taking the slack out of the linkages), then it's almost certainly not the throw out bearing.
It may well be lack of lubrication between the ball and socket of the clutch fork. See posts #12 and #14 on this NASIOC thread.
You may be able to get some lube into the right spot without separating the motor from the box if you use lube-in-a-can with a straw (something like Lucas Red "N" Tacky Spray Grease), but it's going to be tricky to both get the straw in there and see where you need to apply the grease. Maybe you might be able to do it with a borescope camera.
You probably don't want to blindly shoot lube into the bellhousing because it may end up getting onto the clutch, either during spraying or later by being flung about.
To verify if this is the cause you can try to lightly touch the tip of a long screwdriver on the clutch fork while the car is idling and put your ear on the screwdriver handle. Either you'll hear it or touching the fork will make the noise go away if it is indeed due to high frequency vibration--either way you'll have your answer.