Why do that when they can just rent out space in one of their super massive server farms. Think about it... you get some good bandwidth, your data will be mirrored on geographically and topographically separate systems. You don't have to worry about hardware failure or anything like that and you'll be able to get all the bandwidth you could ever want. You don't have to worry about database replication or syncing up data or anything like that, its all taken care of for you. Depending on your needs, you can have gmail, google maps, google office, adsense all integrated with whatever it is you're setting up... web app, file server, database system, whatever it is you're setting up you'll be able to get it from Google along with some nice cross platform tools to make it as easy as possible.
And because of economies of scale the price will be very reasonable, ie. cheaper than rolling your own solution. Hell, I'd consider it, wouldn't you?
"Conversion, fastidious Goddess, loves blood better than brick, and feasts most subtly on the human will." -- Virginia Woolf, "Mrs. Dalloway"