I know of no scanners that use removable media in this manner.
My prediction/hope:
Scanners do away with rs232 and get with USB. I cannot support a SD or MicroSD slot, though. Needs to be a standard USB connector, too. Please, please don't make me go searching all over hither and yon for your wacky, hard-to-find connector (teeth gritting at thought of bc245xlt port connector).
Scanner memory will get large enough to store the entire RR.com database several times over. This is on the order of megabytes for data, freqs, alphatags, talkgroups, everything. Scanner database updates will be seamless and integrated and not unlike syncronization of a pda, iPod or smartphone. Updates could be alternatively loaded to USB drives and updates automatically imported.
Removable media will be primarily for recorded audio. A configurable buffer will keep some duration of received audio in memory for quick replay and review. You hear something cool happening on the radio, hit a button and the previous 2 minutes of traffic is captured along with future tx's. A very small solidstate drive (say, 2Gigs) could store hours of action.
Coming to a scanner near you!