Receptional_Andy - 7:38 pm on Nov 25, 2009 (gmt 0)

if you provide something useful and the oportunity to read/write reviews, then I feel is fine

I wasn't making a judgement on sites with zero reviews - but it's difficult for Google to justify them appearing in results where users are explicitly searching for a review, rather than an absence of them ;)

I wonder why even some major sites haven't addopted them yet

Any code change on most major sites is a massive headache, and will need to pass through a series of judgements on cost/benefit. I imagine microformats are low on the radar even after all these years.

In a way, this comes back to your original title - rich snippets for smaller sites. It seems like a good opportunity for smaller players to get a point of difference in the SERPs.