I suspect this is more of a case of Google gaining mindshare with Apps before charging for the service than it is an example of Google making any sort of shift in strategy.
I think it was more of a 'test' than an 'accident'.
About a month ago I couldn't find the free version, and it took a ton of hunting around to get to it.
I suspect they were measuring the drop in app sign-ups, or if people just would pay.
I'd be surprised if this type of accident would survive a month at google.