Google Apps standard edition is free. The only thing you're saving here is the 5-10 minutes it would take to switch MX records and verify your domain.

Name.com has this built in as well and they're a proper registrar.

I've taken this approach, as well. Given Google's rather complete lack of individual customer support, I do not relish the idea of trying to get a name transferred away from their registrar, in the event I need to.

I don't have any particular experiences with doing this; rather, I'm just being pre-emptively cautious.

How do you transfer them? I've searched for a while and never saw an option in the customized GoDaddy interface that the Google Apps domains use.

You have to email support and they give you a token which you push into a slot that drops a ball that rolls down a chute, lighting a candle which pops a balloon and so on. I don't recall the details, but you can find people who have done it by Googling for it.