Is is possible to prevent OS X firmware password removal? The title pretty much says it all.

I have set a firmware password on my MacBook Pro just to make things a bit harder in case of theft. Still, by pulling the RAM and resetting the PRAM, it would be fairly simple to clear the firmware password and boot into single user mode.

Is there any way at all to prevent this?
In a word, no.  If you are concerned with the contents of your machine being compromised should the machine be stolen a better bet may be to encrypt your drive with FileVault (assuming you are or intend to upgrade to using Lion).  Even if the firmware passwords was irreversible, it would not stop someone simply taking your disk out and reading another way.  The only benefit I can see is preventing a theif from being able to ever use the mcahine he just stole, but frankly this won't help stop your laptop from being stolen in the first place, although it probably would result in it getting binned if it was, rather than re-used and potentially identified at a later date via it's serial number etc.