One of the things I want to try to change at my current work place is to increase the level of developer responsibility when it comes to acceptance testing. What hapens at the moment is a pair of develoers will pick up a card, work on it by writing unit tests and acceptance test then at some point they will decide it's 'done'. At this point it will be 'pushed' to systest for testing by QA. Inevitably some issues will be found and the work will be handed back to development, where it will wait to be picked back up again.
What I would like see is one of the two developers working on the card to take ownership of the acceptance testing and to 'take it to systest' to be tested with the help of the QA team. That way small bugs that are always found in testing can be sorted out straight away. The development would eventually get a better understanding on how other people use their system, defects found in QA are ironed more quickly, thus improving project velocity.