Actually, it probably depends...some elements might be able to be added to the CM7 ROM, others not w/out some work, others maybe not a all...
I would think the dialer would be problemmatic if it's looking for blur contacts and other blur-connectors, same likely true w/messenger. I know that when devs tried to add the blur Email app to GB builds they had to add contacts, the dialer, and other pieces to make it work.
Early this AM I was playing around with this and pulled the blurcamera and mediagallery APKs from a GB ROM and pushed them to /system/app and set permissions, rebooted, and they didn't even show up in the App drawer, and could not be run.