Well, the short answer is that they don't -- at least, not yet. At a Sprint event last evening we had a chance to play with a Tab that had received the Sprint ID firmware update early, and existing packs designed for phones that we tried produced a variety of results ranging from force close messages to weird-looking home screens. That's not to say that the packs can't be designed to support the Tab, of course -- the one for Sprint employees that was pre-installed and designed specifically to take advantage of the extra screen real estate looks great -- but the packs out there now don't seem to play nice. This might explain why the update hasn't been released yet, because Sprint either needs to make sure every pack works with every ID-enabled product or set up the pack store to block Tab owners from downloading incompatible packs. Check out the gallery!
Sprint ID for Samsung Galaxy Tab hands-on