espresso machine & arduino

I'd like to "automate" an espresso machine using an arduino board. The task is not easy. I'm wandering which sensor should I use to measure the pressure. I heard about the freescale's products....I don't know which one to select. Thank you very much, I really appreciate your help

I've not worked with pressure sensors, but there are quite a few resources here on espresso machines. The site search is pretty weak (useless) but a the following Google search of the site has some pretty good results.