If you're looking for some examples, check Zack Arias' seamless writeup:
http://www.zarias.com/white-seamless-tutorial-part-1-gear-space/I'm currently engaged in playing the fun game of "make cyc/seamless work with an 8' ceiling", and it looks like I'm going to end up using a lot of black paint.
There are a number of available pre-fab cyc walls available, if you want something more permanent than seamless but less than carpentry.