Forum Moderators: open
Are microsites still acceptable to Search Engines?
Yes.
...given that they are one page and by definition cannot be as rich in content as multi-page sites?
Says who? You can fit quite a bit of content on one page. I've seen plenty of one page sites that answered all the questions I had about the product/service/topic. Sure you're limited to a degree, but who's to say that quantity = quality?