iOS 4.2.1 seems to be an iOS in which Apple has changed a lot of things, but not all of them represent positive changes. The iPad tablet does not allow connecting any USB device to it, but Apple solved this problem by developing an accessory that allows reading microSD and SD cards but also allows connecting a camera compatible with the USB standard. Well, with the installation of iOS 4.2.1 you will lose the possibility to use this accessory or any other of its kind because Apple has limited the level of energy emitted through that port from 100 to 20mA.
What this means? Well, any accessory that requires more than 20mA to work will not work at all. Here we include not only that Camera Kit but also other accessories that of course need a little more energy to work. This measure was most likely taken by Apple to reduce energy consumption and increase the autonomy of the iPad tablet, but it seems that in the end the customers who bought these accessories suffer. Unfortunately, incompatible with the new "energy regime" imposed by Apple are also: USB microphones, USB keyboards (many of them produced by Apple), flash drives, etc. Practically, the iPad tablet will only be able to be used with very few accessories.
iOS 4.2.1 has quite a few bugs and it is quite likely that Apple will release an update in the near future, it remains to be seen when. I don't know if this limitation also affects iPhones/iPod Touches with iOS 4.2.1, but it is quite possible.
