At the risk of contradicting my current post above, Zarqawi could be *anywhere*.
I expect him to be in the lawless part of Southern Lebanon.
But Al Qaeda has probed several countries with attacks (e.g. subway bombings in the UK, hotel bombings in Jordan, attempted attacks in Saudi Arabia, resort bombing in Egypt, border attacks in Pakistan, suicide attacks in Afghanistan, piracy off of Sudan, etc.).
If Al Qaeda perceives an exploitable weakness from any such probing attack, then I'd expect Zarqawi to rush to exploit it (because Al Qaeda needs a "success" to overshadow their recent string of un-ending failures).
Certainly Al Qaeda's "great offensive" in Afghanistan turned out to be a flop for them this year, and if Israel withdraws and disengages (and builds the wall) in the West Bank, then Al Qaeda will have lost one of its prime Palestinian recruiting grounds.
I think that it's becoming undeniable that Al Qaeda has failed in Iraq, too...though I expect the dust to take a bit longer to settle there.
The Jordan hotel bombing backfire, the failure of Al Qaeda in Iraq and Afghanistan, and the need for "popular" victories leads me to think that Zarqawi will seek to coordinate Hezbollah, Al Qaeda, and Hamas attacks in Israel...and the best place to do all three is from Southern Lebanon.