Google launched its e-bookstore today. The 300,000 titles — about half as many as available for the Amazon Kindle, but probably way more than Apple's iBookstore — will work on iPads, iPhones, Android phones and Google's web-based reader.

They'll also, according to the Wall Street Journal, be hooked in to Google Books, the controversial search service that can be remarkably handy for tracking down page numbers for stray quotes and recipes in books you already own. That will give the service a little bit of a leg up, and offer some consolation for the fact that Google's e-books are totally incompatible with the Kindle. But buyers will have to factor in that Google has grown wary of some of its past experimental products and simply shut them down. Given that access to Google's books are controlled by Google's servers, customers will have to pray that doesn't happen.