It does make me wonder why there have been no attacks on the regime but all sorts of attacks both the citizenry and westerners. Just how eager is Al Qaeda & Co. to depose the royal family? We can't trust either side, that's for certain.
Actually this is a perfect technique for Al Qaeda: By not attacking the Royals directly they insure that their funding continues; by confining the attacks to foreigners within the Kingdom they will ultimately cause the House of Saud's downfall -- by Westerners!
It's a perfect leveraging of their rather limited power.
Al-Qaeda wants the royals deposed, probably executed, and the terrorists in control of the country (and of the oil fields.) Osamu Bin Laden had been a big push in the anti-royals faction for years, having gotten started protesting the US military bases set up on Saudi soil for Gulf War I.