A500 ICS ROTATION PROBLEM SOLVED!
1-Install free AutoRotate Switch app.
2-Click on the app to switch ON auto-rotate.
3-Turn the A500 off.
4-Turn the A500 on.
5-Auto-rotation works perfectly!

1-Install free AutoRotate Switch app.
2-Click on the app to switch ON auto-rotate.
3-Turn the A500 off.
4-Turn the A500 on.
5-Auto-rotation works perfectly!
There has apparently been a breakthrough on at least one of the sensor driver problems by a developer working on the ICS leak at xda-developers. I am hopeful that this may be related to the auto rotation lockup problem many are seeing (described above), and that this fix gets passed into the official Acer source if it is the solution. See: [ICS PATCH][CWM] Dear XDA, I present to you...the rotation fix- xda-developers.
If someone at Acer already fixed it, then that's great also.