Was searching around the web for better Exchange solutions (due to some of the limitations of the built-in app) and found this thread:
HowardForums: Your Mobile Phone Community & Resource - Exchange on Droid w/ Signature! & More!
Someone pulled the "Work Email" app from the HTC Magic (I believe). I installed it on my Droid and it works great! Supports a signature and also GAL lookup.
The only issues I see so far is that it appears to maintain its own internal contact list (pulled from Exchange server) and it also doesn't have a built-in calendar. For the time being, I am leaving my sync settings to 1 day in the built-in email app so that I continue to get Contacts and Calendar entries sync'd.
Hope it helps someone!