...in the cloud, hence it aims more at being a glue for the web. Merge datasources from anywhere, create joint reports, an incentive for everyone to open-up their data and make it accessible to Google. Sounds like a smart idea to place Google in the middle of the web.
Yep, Tableau does have a cloud version too - both private and hosted.
Also worth checking out is http://redash.io for this kind of stuff - fairly new but developing quickly and very easy to hack on/add stuff. Good docs, easy to deploy and has some nice auto-update reports bits. We use that quite heavily. Its open source/free to use but also comes with paid cloudy plans.
Thanks for mentioning Redash! (I'm the author) It's actually not that new -- I've been working on it for 3 years now :-)