I already see the Stallmanites rallying for their battle cries. Never using anything you didn’t write yourself is an asinine concept, in my opinion… This coming from someone who can write web services himself. The truth is that using services “in the cloud,” “on the web,” or anywhere else is just like using local software in one very important sense. (I particularly like one comment I heard on this once which went something like: “Would you be able to validate the source code to the ls binary on your own?”)
If your data is not in two completely separate locations, then it’s not safe.
My wife, who’s in need of some extra storage space (shes starting to get into photography some) got two external 120gb hard drives (which were on clearance.) Before I let her use them I sat her down and gave her some important advice: “If you store your data on one of these drives… it is NOT backed up… it’s just stored on that disk. And if something happens to that disk there is NOTHING that I can do to save your photos. Period. I bought you two because every so often you need to copy whats important to the second disk. That was if one disk dies, you don’t loose your stuff”
I’m not sure why people feel that if they’re using apps in the cloud that this doesn’t apply to them. A service shutting down is basically equivalent to loosing a hard disk. Be prepared. Back your data up if it’s that important!
As an aside. All WordPress installations allow you to export your data — even WordPress.com. I suggest people take advantage of that on occasion!