Patzold and Greiss are definitley the leaders of the pack IMO, but Ehelechner is more mature and furthur along then Greiss so expect his impact sooner.
Both goaltenders look like young Nabakov's .... no joke... Patzolds improvement from this year from the past was dramatic, and really caught me off guard.
He's always been an athletic goaltender with excellent reflexes, but this year he worked on the mechanics more and he looked much better for it...his rebound control has come along way.
IMO He's the #1 goaltending prospect in the system, but apparently you ask the Sharks staff, and they say Greiss is.
Here is a great article on Sharks prospects, including goaltenders.
http://www.nhl.com/futures/features/prospects_san080905.html
Also the Sharks added Alex Stalock, USHL Playoff MVP, and Taylor Dakers, a good prospect stuck behind a better on in Jeff Glass in Kooteny.
Greiss has the biggest upside, but he's still very raw and has alot of development ahead...much like Nabby had to.
Patzold is coming along very nicely and I expect him to get more action this year in the AHL, and be Clevelands go to guy.
I also hear from fans in Cleveland that Dimitry is an awesome person. Good guy.
EDIT: I only saw Greiss play vs Canada at the WJC, and he looked pretty impressive, you couldn't fault him for those goals, mabye Stewarts five whole from the side slot, but other then that I was impressed with his reflexes, poise, and athleticism, very strong laterally and excellent flexibility.
Sharks lack a top end kid, but they have a lot of raw talents and with Strewlow developing them, anything can happen.