Today I'm working on the new Ratings feature of SharePoint 2010. I think I had the same issue than everybody when enabling it for the first time : the ratings don't refresh.
I enabled the Ratings on a Custom List and rate two items for testing purpose. And guess what? The blue stars are not showing!
So I read some blogs which speak about the "Social Rating Synchronization" timer job that must be runned to aggregate the ratings. Actually here is the description of the "Social Rating Synchronization Job":
Timer Job to synchronize rating values between Social Database and Content database
And here is the description of the "Social Data Maintenance Job" (another timer job):
Aggregates social tags and ratings and cleans the social data change log.
So I think this is clear. You have to run these two jobs if you want to see your ratings refreshing.