I remember a thread with a similar idea at OperationSports.
Improving the atmosphere and crowd reaction is big thing for 2k9.
At OS they said that it would be cool if every player had different crowd reactions in every city. Certain players like KG or AI will still get cheered in Minnesota and Philly.
Or if a player like LeBron's makes a big play/dunk he also gets cheered in every city, they got love for him all over the country (maybe except for Washington lol).
Then there are specific players which should get booed, like you said, for things they did/said in the past. Wade in Dallas, Stevenson on Cleveland, etc ..
There were also a talkin about adding crowd chants to the game at OS.
In Toronto they scream
"Jose, Jose!" in shape of "Olé, Olé! ", or in Boston they cheered
"Rondo's better!" against Mike Bibby and the Hawks, just to show a few.
That'd be extremely cool also.