He certainly has the motive to support it. If he can keep the battle in Israel going, it makes it much more difficult for the US to line up support for invading Iraq.
So, if he's not behind it, he's totally stupid.
I think Saddam has bad judgment, but I don't think he's totally stupid.
I think it's part Saddam, part al Qaeda, whether working in concert or not. It's a mutual interest of theirs to get us involved in the Israeli-Pal conflict in an attempt to divert our attention from them.