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In an unprecedented move from Apple, it seems that the iPad Camera Connection Kit accessory, the one meant to pull photos via USB (or via an SD card) from your digital camera to your iPad, does more than expected. Users that are purchasing it are reporting they can connect some USB keyboards, audio headsets and such and use them accordingly. From my point of view I believe that’s a small error from Apple, which will be ‘fixed’ soon with a firmware upgrade or else you would have no reason to buy the keyboard dock for 69$, if you can get your own 10 bucks keyboard to work.
There are also limitations to the iPad Camera Connection Kit, like the fact that USB hard drives are not recognized and the same stands for a lot of video equipment. Also the transfer is only one way, from the external device to the iPad, no way you can get the files backed up for example on a flash disk or SD card. Plus not all transferred files can be viewed on the iPad, mostly because the lack of adequate software to open the files. Maybe some apps will come down the road in App Store but I doubt Apple will allow their device to do more than they want to.

iPad Camera Connection Kit
If you’re looking for iPad Accessories you might want to check out this article.
Source: Gottabemobile