That's Blogger the service company, who were probably largely responsible for the early explosion in blogging, now owned by Google.
Chris Messina's posted an open letter, commending them on their recent service updates, and requesting that they support microformats, with quite a bit of information on why they should. Yes sirree, +1 to that. David Jane's added his voice, in particular in support of hAtom. (Though I'm not sure he mentions my favourite use case: more machine-readable archives, Atom/RSS feeds are forgetful).
One caveat, a mistake a lot of folks made with Atom was adding support for Atom 0.3 without factoring in that there would be changes for Atom (final, RFC 4287). I think this will be considerably less significant with the established microformats, except for one point: few of them have designated profile URIs, though it has been agreed that they should have them.
As these need to go in the <head> of the HTML, I'd suggest (in the cases where there isn't a microformats.org-endorsed profile URI yet) using a placeholder URI in a controlled namespace, e.g. Dan Connolly's done a provisional profile for hCard (W3C domain), I've done one for hReview (a domain under my control).
It's important because the profile URI allows the publisher to say unambiguously this is what I mean, rather than it being left to the client to assume the meaning based on scraping simple attribute strings (like "vcard"). It also enables elegantly automated extraction techniques like GRDDL.
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