Okay, lets get some of this confusing stuff out of the way: the Samsung Focus has "only" 8GB of storage available. In talking with Samsung, their position was basically so much of this phone is "cloud based" that 8GB may be sufficient for most people. However, they're more than glad to suggest that 16GB and higher are probably on the horizon.
Having said that, the Focus does have removal storage (see the above shot), but it's tricky. Basically you can any size card you like, but you can't remove it without hard-resetting the phone and it's not clear that the card would be re-usable if you do remove it. So essentially, if you add a 16GB or 32GB card, that's it, you got your shot. This has to do with how WP7 uses memory--basically it mirrors/spreads it across any added memory.
But hey, our EVO came with a 16GB card and we've never removed it either. Seems like once you go that huge (or larger), you have little need to keep swapping. So to us, this sounds like a win-win situation, at least for what we're working with here.