Theistic evolution is a term that Howard Van Till came up with. There are basically three types of "creationists." There are the young-Earth Creationists (YEC), and these believe in the literal intepretation of the book of Genenis. There are the progressive or old-Earth creationists (PEC), and these believe the book of Genesis to be figuratively true, but not literally true--i.e. the 'days' are really astronomical periods of billions of years. The Intelligent Designers fall under this category.
Then there are the Evolutionary Theists (ET), which believe in (1) God, (2) the Big Bang, and (3) all of evolutionary theory--macro and microevolution, as some IDers like to split hairs. Basically, ETs are like Deists (who believe that a God started the universe and took off from it; Paul Davies is a famous example), but they also believe in a personal and providential God that you can pray to.
Van Till's writings are quite interesting. Writings by Dennis Lamoureux * are quite interesting as well. He discusses the different points of view, and decomposes quite rigorously the book of Genesis to show its hermeneutic constructions and context. Lamoureux calls himself an Evolutionary Creationist, but this is basically the same position as ET--not PC.
* Disclaimer : I am a friend of Lamoureux's, and he is an active and prolific player in the Creationism scholarship. I'd recommend reading his textbook title 'Evolutionary Creationism'. His debate with Phil Johnson (head of DI) is quite entertaining too.