This was how I got to work today. It’s really the first time I’ve been on a MTB. I usually ride my road bike and use a messenger bag for all my “stuff”.
Using a MTB might be easier for a commute because it’s a little more solid especially when using panniers. (It also might give me a way out, into the shoulder, if I’m run off the road by a motorist.)
Last night I decided to take some time to put on the Quattro pedals we bought for it a while back, put the cleats on a spare set of shoes, and also put on the quick release rack. I pumped up the tires so it would be ready to roll.
I think I was a little excited about riding a different bike for my commute because I was up before my alarm. Instead of dawdling, I got up and ready to leave a little earlier, knowing the bike would probably be a bit slower. Also I wanted to stop off at the store on my way to pick up some fruit for snacks. I knew I would be able to manage it easily with the panniers on the bike.
Today was really a test for me in that I want to commute more by bike. Sometimes an errand or the amount of things I need to transport is a limiting factor. If I can manage ways around that with a different bike then there are fewer excuses not to velo-commute.
Maine Velophile 
Bike commuting rocks. When you get more into it, that quick-release rack might not hold all your stuff. Want a good deal on a Bailey Works messenger bag? I bought it at BBB, used it once… I didn’t like the way it felt carrying a large laptop. (duh) I like a plain old backpack now.