Google Wave is in preview phase at the moment described as "What Might Email Look Like If It Were Invented Today?". With waves/conversations containing from as little as one to thousands of people, pasting comments in one wave can mean that it gets exposed to alot of people quickly.
Email today can't cope with lead collection within the email. This enables it. Is this the new email newsletter? Could this act as a kind of corporate sponsorship for twitter like read-only waves?

At Magnetise we've been playing around with Google Wave recently and overall we're impressed with the rich user experience. Why not check out our In-Banner Google Gadget for Google Wave:

http://www.magnetisemedia.com/inbanner/demo_google.pdf

As with such things, its easy to spam people, we need to see how Google Wave matures and utilise it appropriately.