There is a very helpful blog post from PMChampion about the changes to the PMBoK (version 5 has been released) and the exam change that follows this.
( http://www.pmchampion.com/blog/pmp-exam-prep/new-pmp-exam-dates-released/ )
If you are taking any of the exams in July or August (this year 2013) this blog helps you identify which PMBoK is being used for the exam (remember PMP is a knowledge based qualification so you need to be using the right body of knowledge).
The blog also lists the changes to the PMBoK between versions 4 and 5 - more on PMO, up from 42 to 47 processes. stakeholders are in, communication has been revised, time-cost, scope and cost also updated.
Happy studying folks.