No, it was in 2010 that Jupiter gets ignited into a star, of that I'm absolutely sure. It was a good book, better than 2001 IMHO. In the very very lame sequel 2061, he expands on the consequences of Jupiter being a star and the availability of all the diamond that was ejected from the initial ignition (space elevators, etc.). In the utterly benighted and horrible 3001... well, frankly, it was just too awful to be described.
Qwinn