Aha, well, you could download the binary of beta8 (or beta9), but if you want to build it, see [archived] Building Syncthing. Super short version that might work:
export GOPATH=~
go get github.com/calmh/syncthing
cd ~/src/github.com/calmh/syncthing
./build.sh setup
./build.sh
ls -l bin/syncthing