Yes, it's within his Presidential perogatives. No, it really, really wasn't a good idea. Really.
Other Presidents have done the same sort of thing. It is not uncommon. But prior example is not justification for a maneuver so nakedly political.
As I said in an email to a friend, it seems President Bush, in the last two years of his administration, is determined to self-destruct as spectacularly as possible. The Republican Party is coming apart (not necessarily a bad thing, since political parties do not seem to be particularly good for democracy) which will make the 08 elections easy pickings for the Democrats.
All this just as what seems to be the biggest conflict of cultures since World War II looks to be shaping up. Well done, gentlemen. Well done.