I just wanted to post my recent experience with our dishwasher not draining at the end of the cycle. Initially it started with small amount of water left at the bottom. Few days back there was more water. After some poking around and web searches, I checked the air gap on the sink, next to the faucet. The pipe end inside was completely clogged with some lint like stuff. After I removed the clog, the dishwater started draining properly. Cleaning up the air gap was was simple. I pulled out the cover and then unscrewed the base.
Hopefully this will help others with similar problem.
-Dipu