While I'm not surprised that the Exchange 2007 Outlook Web App doesn't work on my Droid X, I'm still disappointed.
The Outlook Web App is actually not that bad, and while I initially really liked the Droid X, its actually decreased in reliability, and over time, I've discovered I have many complaints about it, such as the poor keyboard performance and the not-so-intelligent type ahead.
There are a couple things I like about the Exchange 2007 Outlook Web App, such as the calendar. In general though, I can't accept that Microsoft doesn't support any other mail clients besides Outlook. That is totally anti-competitive, and I wouldn't be surprised if the Department of Justice took their butt back to court!
UPDATE: I was wrong! Exchange 2007 Outlook Web App does work with the Droid X browser. One of my co-workers also has a Droid X and said it worked for him, so I gave it a second try and voila! Indeed, the Outlook Web App (OWA) in Exchange 2007 does work with the WebKit-powered Droid X browser. The screen is tight, but its definitely usable and useful.