This is an easy job, only taking a few minutes to do, but when I
    went to lift up the heater, my left hand got wet.  Hmmm... blue
    goo... :( Coolant is leaking ever so slowly from the max/min
    valve.  It appears to be coming out of the shaft of the lever
    that goes into the valve. There were no puddles, but after I
    disturbed it, it would leave a drip about the size of a dime
    *when the engine was cold*.  As the engine warmed up, it didn't
    leak.  Yeah, sure... make me insane!
This is *exactly* what mine did when I bought it a few weeks ago. The 
valve is available separately for about $100 at the dealer. Mine is 
now fixed, but the heater core itself leaks. I noticed some dried 
coolant on the core before, but hoped it was just the valve dripping 
onto it. No such luck - I have to take it in *again* to have the core 
checked & replaced. I'd suggest popping the front piece off the 
heater so you can inspect the core. Mine has a white buildup along 
the botton 1/2" or so of the aluminum fins.

    Does anybody know if these valves can be changed independently
    from the heater core?.. it looks like it all comes apart, but who
    knows how VW sells these parts.  The Bentley doesn't say much
    about this heater, and is rather disapointing.

    This is a major bummer... just had the cooling system pressure
    checked last week, and coolant flushed. 
Tell me about it. The dealer pressure test failed to locate the leaky 
valve, and *another* test failed to find the leaky core. Apparently 
you can replace the core/valve without bleeding the system - just 
clamp the hoses first then fill the new core/valve using the bleeder 
screw before opening the clamps.

Good Luck.

Shawn.