Go 1.1.1 is now available for download on code.google.com: https://code.google.com/p/go/downloads/list I have verified using my own overlay that simply bumping the ebuild version number (and the associated patch version number) is sufficient for successful compilation and installation. I have also verified that the resulting binary works as expected (via "go build -v -a" on an existing golang project and running the resulting executable successfully).
This has been added to the tree. Thanks for the report.