After trying the new Vista build, i can say that i can see a lot of changes in the task manager part. Screenshots have been provided at the end of this post to show you what i am trying to say. The Task manager has remained the same since its introduction in Windows NT4, little changes have taken place but nothing major. Take a look at the screenshots and you will come to know that a lot is being done in the task manager part. Task manager now comes with something called virtualisation and also has the services tab. I am not sure if the task manager was changed in Windows Vista Beta 2 Build 5384.
All Screenshots have been taken from Build 5456 which was released recently.