Internet Haganah (thanks to Ron for the heads-up) notes that an Al-Qaeda site has posted a map of Vienna with a site marked:
This is an underground parking garage [tiefgarage] in the center of Vienna in the immediate vicinity of the Vienna State Opera House, the Grand Hotel and numerous other tourist attractions. We don’t have enough information yet about the file, who posted it, who is linking to it, etc., to be able to accurately assess whether this is a potential target, and if so, how great and imminent a threat it is. However, in light of what is above the tiefgarage…