According to a story over on iMore, Apple is preparing to drop the traditional dock connector currently found on the iPhone, iPad, and iPod and replace it with a smaller 'micro dock.'
The idea is that the current dock is a pretty big piece of kit, taking up valuable space inside devices such as the iPhone and iPad, space that could be better put to use by an LTE chipset or maybe a slightly bigger battery. The following image gives you an idea of how much space the dock takes up inside the current iPhone 4S:
Image credit: iFixit
Here is the complete dock, stripped out of the handset. It consists of the dock and the primary microphone:
Image credit: iFixit
As iMore pointed out, there is precedent for Apple doing this. It switched from the ubiquitous mini SIM card to the then far more uncommon micro SIM. It also took the antenna out from the iPhone and built it into the frame of the handset.
Now you might be thinking that Apple won't do this because it would make a whole raft of accessories obsolete. Well, yes, but you can never guarantee that an accessory built for one device will work on a new device anyway, so this is a moot point. It might make it harder for manufacturers to who make things like docks because they're have to somehow cater for two different connectors, but again that's not an insurmountable problem.
One of the reasons that the dock connector is so big is that it is a separate component, that connector alone takes up a lot of valuable space. Apple could make it take up less space by building it onto the mainboard, but I guess it won't do this because the connector is a weak point and replacing a dead one would them mean replacing the whole mainboard.
The inside of an iPhone is petty tightly packed with electronics, and every cubic millimeter matters. But that said, the best evidence that iMore can offer up for this is that they've 'heard' that Apple is going this. Given that alone, I'm going to put this 'rumor' into the 'I'll believe it when I see it' pile (along with all the other iPhone 5/iPad 3 rumors).