My seat and seat post was stolen off my commuter last week too. I was so annoyed. I had been parking my bike in the same place for over a year. It was just the stock seat and post but they both had shock absorbing qualities. I hate the new one I got so now I'm going to try something else. VERY annoying.

I will get a locking seat post clamp now though instead of the easy release one.

I feel your pain. Mine wasn't expensive so I can only imagine how annoyed you are.