Flutterby™! : .NET condition variables

So bouyed on by Ken's "that one was free, 'cause it's their bug" .NET success this morning, I figure I should learn a little: Any of you .NET cats out there know what the idiom is for condition variables? Locks are no problem, but it seemed to me like condition variables were caught up in some funky notion of thread protecting classes and I didn't chase it any further 'cause the .NET semaphores did what I needed. But condition variables are so damned handy when you're doing threaded apps (which should be "never", but that's a rant about the capabilities of operating systems and interprocess communication) and I haven't found them searching the knowledge base.