I think it would be great(if the news is true that is) to have two movies. There is so much going on in the seventh book that I don't think it would all fit in well in one film. I am sure that all those who have read the book will probably agree with me..
There is a rumour going around that the last Harry Potter movie (which is based on the book Harry Potter and the Deathly Hallows) would be split into two parts and also that Steven Speilberg would be the director! Read this article which appeared in the Daily Mail.