It supports the four major types of flash: SmartMedia, CompactFlash, SecureDigital, and MemoryStick. The 9-in-1 just means that it supports the additional flavors like MMC, miniSD, MemoryStick Pro, MicroDrives, etc.
I don't think the reader supports xD directly but you can get an adapter that plugs into the CF slot. These usually run $45 so it is cheaper just to get a dedicated USB xD reader. Be careful as there are some cheap SmartMedia to xD adapters that only support <128MB xD cards.
I really don't use mine since the transfer rates on Compact Flash and Secure Digital were about 30% slower than my YE-Data reader I have now. However, it seemed to work fine with the 4 GB CF card I tested it with.
There will be a new Dell 24" panel coming out in a few months ( probably around March or a bit earlier.) It is supposed to be compatable with Vista and have a faster refresh rate.