Same here - updating the camera now.
Unfortunately there are no improvements promised for servo AF.
Here's the link: http://www.canon.co.uk/Support/Consumer_Products/products/cameras/Digital_SLR/EOS_M.aspx?type=download&page=1
My main issue with the single shot AF previously was that under certain conditions, specifically when there was any motion while the camera was trying to focus, the camera would often refuse to lock focus. It would just give up and change the focus box to red. That appears to be resolved completely with this new firmware update - so that's great news.
I'm looking forward to testing it further.
How is the performance of the camera overall? Does the new firmware make it a better camera to lock focus more confidently and snappy? I wanted to update mine, but unfortunately the camera is at the other side of the world and won't be back to me until 10 days later.