It can be either of two things depending on how the key doesn't come out.
If you can rotate the key to all positions (ACC, Lock, Off, Run, Start) and while in the lock position the key will not come out, You have a bad lock cylinder. About the only recourse is to replace it OR have a locksmith rebuild it.
The second common problem is that the key will NOT rotate back to the Lock position to allow key removal.
With a floor shift the common problem then is a bad solenoid on the key cylinder. You have two options. Look under the plastic shroud under the key switch location. You will find a small plug that you can remove. Then stick a pen/pencil or similar into that hole and you will find a plunger. Push that plunger UP and the key should rotate back and release.
OR you can remove the shroud itself (you don't have to remove the steering wheel, it will come off, it's a TIGHT fit but it comes off) Then remove the one screw retaining the solenoid, release the clip on the bottom, disconnect the wiring. Throw the solenoid into the junk bin. Reassemble the shroud and drive happy.
On the column shift this solenoid is replaced by a short cable. Just remove the cable.
Tuesday, June 16th, 2009 AT 1:18 PM