There seem to be two different official Parallels forums. The other one has almost nothing, yet seems to be easier to get to by accident. This one: http://forum.parallels.com The other one: http://community.parallels.com/forum/
The forums are separated as they are aimed for quite different purposes: forum.parallels.com - is mainly a tech. support forum. You get a link to this forum when you purchase Parallels products along with links to support webpage and Knowledge Base. Here you can discuss various technical issues with Parallels support staff, developers and other customers. community.parallels.com/forum - is dedicated to discussing PVA (Parallels Virtual Appliances) usage and features and also for answering some general questions from the visitors who are interested in Parallels software. Consider it a PVA enthusiasts community, thats where forum's name come from.