One of the other stories claimed they said it was because (last Thursday) the NYT and Ars Technica reported it. That's what Google said, but of course they didn't have to confirm the stories (and I think they haven't on previous occasions unless it suited them).
So your question remains: why does it suit them now? (Guessing), perhaps part of their evolution into a huge corp?
Wild speculation: perhaps they are trying to get out in front of upcoming announcements on actual products to show they are working in this space too? The crunch pad is due out soon and Apple is also believed to have a product in this space as well. If they put this out there now, any publicity for similar products on blogs and news articles will also likely have a blurb that "Google has also announced they will enter this competitive space..."
Im pretty sure google base can be written off as a failure - not total since its still in operation. But it was supposed to be a repository for product information that google could throw into search results like video and news.
