Why is the Docker Client so old on Windows

Just update to Docker 1.10 and the client on Windows is still lagging behind. Why is this?

Client:
Version: 1.8.1
API version: 1.20
Go version: go1.4.2
Git commit: d12ea79
Built: Thu Aug 13 02:49:29 UTC 2015
OS/Arch: windows/amd64