2K Sports just posted another NBA 2K11 Developer Insight. This one talks about the expanded playcall system.
"All Teams Are Not Created Equal - Each team has a base playbook of at least thirty plays that reflect their coach's philosophy and style of play. The marquis teams also have additional plays available to them that they can run for additional flavor. We created individual sets for teams as well. What this means is that even though two coaches may use a floppy set, their personnel and style may dictate that their floppy set starts differently than that of another team that runs a floppy. Now even if teams run plays that have the same end goal, the look you get from team to team will differ based on how they run it and who they run it with.
If you consider that we have well over 1000 plays across all the current and the old school NBA teams, you will see that, as a User, you have a plethora of options to vary your offense."