OpenGL 4.1 Review: http://www.g-truc.net/post-tech-lastest-full.html

Christophe also published an updated version of his sample pack, with a nice table showing how the new stuff works on both NVIDIA and ATI (Beta drivers): http://www.g-truc.net/post-tech-lastest-full.html#post0321

UPDATE: Another good article about OpenGL 4.1: http://rastergrid.com/blog/2010/08/an-introduction-to-opengl-4-1/