Thanks to everyone that reported they had no contacts. A pattern is emerging. Almost all the users reporting lack of contacts have the same problem, which in fact isn't a new problem nor is it related to the recent reliability issues. This blog article has the details. If you have a lack of contacts, or indeed any problem, please log into our web site and check your account status first (if you see a red light that indicates a problem that needs to be fixed), then your sync status. These pages 'understand' a large number of known support issues and will often display information on how to fix the problem you have.
Update: thanks to a very helpful user who was willing to allow us to use his account for debugging, we found an additional problem with Google contact sync last night. Users with larger numbers of contacts should benefit from the fix which is now live on the production service.