In case you haven't been following the tons of articles trashing Apple's love of skeuomorhpism and praising Android's move to a minimalistic interface, I'll give a brief overview.
First, to define "skeumorphism." According to Wikipedia, skeuomorphism as used in the design world is "an element of design or structure that serves little or no purpose in the artifact fashioned from the new material but was essential to the object made from the original material."
Secondly, an example known to all Apple lovers, the contacts app:
Apple is known all over the world as one of the most innovated companies in history. They're hardware is beautiful. Constructed with attention to the most minute details. They push boundaries on their hardware; making it smaller and sleeker every iteration.
So why does a company that produces such beautiful ground breaking hardware have interfaces that haven't changed in 5 years? Why do they base the digital off of the physical?
Most reasoning for the use of skeuomorphism is to tie in visual of the "new," the digital with the visual of the physical objects people are used to using for the same tasks. This idea makes sense 5 years ago, when the iPhone brought a whole new meaning to hand held devices. Making the user comfortable with the actions they would be performing on a phone instead of on paper was paramount to their success.
Now, however, users are used to performing these actions on devices. It's time to share the innovation with the OS. Use multitouch to it's maximum, not it's minimum. Buttons should be replaced with gestures, change screens no longer needs to look like the turn of the page. It's visually wasteful. Their efforts on perfecting that leather stitching should be used on perfecting user interaction. Android has started to do just that with Ice Cream Sandwich and Jelly Bean, let's hope Apple starts seeing the importance of creating experiences true to the device instead of it's physical predecessor.
Articles on Skeuomorphism: