Latest release is on Pharo 6 (https://clementbera.wordpress.com/2017/07/19/sista-open-alpha-release/)That's the release where the published benchmarks happened and where multiple developers got involved.
No plan to release on Pharo 7 alpha. Ask again once Pharo 7 is released.
Repository is in migration though, I migrated to github earlier this year, but with recent changes & new organization, I think the repository will be merged with open-smalltalk-vm repository. Documentation will be merged too, so it's going to be easier to build images and matching VMs or move code from VM-side to image-side or the other way around.
I think questions related to Sista should be on vm-dev since there are only alpha releases (i.e. no interest for non VM developers).