Very recently I published a post on the flat design trend which is coming back and will be popular in 2013. That post was very popular, one of the most popular on the site. Many seem to be a fan of flat and minimal UI design because it looks so clean and professional.
However skeuomorphism isn't something that should be forgotten about. Skeuomorphism is when computer generated graphics are made to look like real life objects, whether it be copying a real life texture, or making a button look like a real life button. Apps are great places to use skeuomorphism and Apple's iOS platform is predominantly known for it, with many of its own app using the design trend. Here are some brilliant examples of other designers using skeuomorphism in their apps and UI mockups.