As the name suggests, 7 Wonders: Wonder Pack includes new wonders for use with the 7 Wonders base game, with the wonders in question being:
The Great Wall of China - with the owner being able to build the stages of this wonder in any order (since the wall is, of course, a long horizontal wonder and not a primarily vertical one)
Stonehenge - with the amount of stone you have being important during its construction
Abu Simbel - in which leaders can be buried and mummified for bonus points
Manneken Pis - which is a revised version of the 7 Wonders: Manneken Pis wonder first released as a promotional item at Spiel 2010.