3.5 VS. 4.0

Tasks
3.5: 340+
4.0: 340+
Both versions currently contain the same tasks. There is no immediate plan to change this in 2010

Loggers
Only 4.0 will deliver MSBuild Loggers

Task Factories
Only 4.0 will deliver Task Factories

Active Development
Both versions are under active development. There is no immediate plan to change this in 2010.