I found an app in the Market named AutoAnswer, which auto answers calls when they ring.
Here is a comment from the Market:
Finally...a stable and well written for my Droid. I can use handsfree or on bike riding and keep both hands on wheel. It even bypasses the slide lock.
I would think, based on this, that an app could be built that would bypass the lock screen, and give the caller ID screen with an answer button instead of the swipe to answer. If I were a developer, I would give it a go, but...I'm not. :redface:
Edit: The app is free and open source.