[citation][nom]hellwig[/nom]Class shouldn't matter, if you have a Class 6 card it should run in a class 2 slot, and vice-versa (just like SATA 1.5Gbps drive should run in a 3gbps slot or DDR3-1600 RAM can run in a DDR3-1333 slot). Yes, Class 2 is slower, but you aren't using the card as RAM, just storage. And as for USB charging, my G1 can charge over any mini-USB cable, but it uses a special usb cable for data, you have to ask HTC why (however, I think they fixed this recently).[/citation]
You do realize that you can run your apps off the sdcard, so the just storage philosophy doesn't hold water anymore. I can't speak for the WP7, but WM6.5 and Froyo allow for installation of apps onto the sdcard.