Hi, im going to be buying a t500 this summer, i dont know much about how often lenovo updates thinkpads with respect to when suppliers announce new products, but what are the chances the t500 will have the newer nvidia gt1xxm or the ati radeon hd4xxx?
While Lenovo does a very good job of using current components there's no way to predict just when certain changes will be made. There are simply too many variables involved in making a change to an existing ThinkPad model. Thus the question becomes very similar to the age old question "when is the right time to buy a new computer?"
What I might suggest, is to focus on when you "need" the computer and make your purchase then. I would suggest, that if you absolutely must have the most powerful graphics solution, you take a look at the W500. I use one for my 3D design and other graphics intensive applications and it's a great machine.