Had the same problem myself. Try this. It worked for me.
TO CONVERT 9/1/2011 9:52:00 AM TO "Sep 1" or the like follow these steps.
If your data is in B6, use formula below:
=TEXT(B6,"mmm d") or
=TEXT(B6,"mm/d/yyyy") depending on your preferred date format.
Once you get the "Sep 1" output, Copy and Paste on the same cell using ALT+E+S+V
Hope this helps