Why does my power socket for my MAC and my iPhone charger get so hot?

It's hard to tell from your question what you mean by "so hot." It is normal for a charger to get pretty warm when charging. Following is some general information on transformers that may help explain that: http://www.copper.org/environment/sustainable-energy/transformers/education/tran s_efficiency.html

If you think that it is significantly warmer than in the past or that something else may be wrong, it would be a good idea to take it in to an Apple Store or Authorized Service Center to be checked.