Apple’s original Camera Connection Kit isn’t the most brilliantly engineered product Apple has made. Two separate adapters is hardly necessary to get both USB and SD input, which third party accessory manufacturers have demonstrated by putting all both in a single reader- and more.
One no-name manufacturer has now crammed 3 extra features in there. The USBfever 5-in-1 reader has your standard USB and SD, but also packs a microSD reader, mini USB for syncing/charging and a 3.5mm jack for composite video out. At $45 it’s rather expensive- especially if you don’t need the video out, and the danger with such no-brand accessories is that Apple releases a FW update that renders them useless (something you don’t have to worry about with Apple’s own product or officially licensed third party accessories).
Among the other third party kits out there is a CF (Compact Flash) reader/USB combo, which should be useful for professional photographers who use CF cards in their DSLRs (*points at Mathis*). Of course you could just buy the official kit (or any other kit with USB) and use a CF reader in the USB slot, but at least this solution is a bit slimmer.
I have to point out what I’ve already said about iOS devices and proprietary accessories; they use that 30 pin connector for a reason. Combine the two accessories above and you have 6 “holes” in your shiny new iPad 2 that will add to all the others; VGA, component out, HDMI out, line-out, line-in etc. Adapters are the way to go with devices that support this many accessories (some interchangeable), or you end up with an endless debate on what’s more important.