I have posted an article on SQL Server 2008 partition level locking. You can browse it here: http://sqlservergeeks.com/articles/sql-server-bi/73/sql-server-2008-%E2%80%93-partition-level-locking
This article demonstrates partition level locking behaviour which is new in SQL Server 2008 onwards. Locks are escalated from ROW to TABLE by default. But the default option can be changed to escalate ROW locks to PARTITION locks. This article demonstrates and explains how you can achieve that.