This isn't true actually. GV voice email is really really easy to set up on any Android phone. I have it on my Fascinate (VZW bloat on board) working fine. I use just the visual voice mail part of GV and I love it, and it works flawlessly.
Perhaps you meant something different though above, if so I apologize.
I just meant the Visual Voicemail part, that's built into the phones software; not the email or GV itself. Like you said GV is visual itself when you open the app or when you receive emails or text when getting a message.
I've got GV to work well on all my Android phones and, even the Iphone but, the visual voicemail part was always tied to the carrier.
I think people are concerned that Verizon will try to take over the visual voicemail that seems to be built into ICS now. After thinking about it, I admit I'm concerned about this also since you can't use the VVM built into IOS on the Iphone unless you connect through VZW. ( I could be wrong because I haven't actually tried it)
I'm leaning to thinking it won't be a problem based on how they showed it working in the presentation. Like hyperdude mentioned, when you miss or ignore a call, it will show up in the call log as a visual message, no matter what you choose to use for your voicemail GV or VZW.