webOS has excellent support for Exchange, though I've read there is an issue with fake-Exchange accounts such as Gmail.
Palm licensed the necessary stuff to support Exchange within webOS, so it will be around for as long as Exchange is used by enterprise companies.
webOS does not, however, support ActiveSync, nor will it sync directly with Outlook. There were a couple sync solutions, but those don't support webOS 2.0 (not yet anyhow).
But if you're using Exchange, then you shouldn't need to deal with syncing directly with Outlook. The Pre2 should be fine.
In the meantime, you could just download the webOS 1.4.5 SDK (that one is public) so you can get used to webOS and see how you would set up Exchange and if it works for you. I don't think the email app has changed much, but I don't have my Pre2 yet, so I can't really say for sure.