The D-GSM implementation is now complete and merged to the OsmoHLR master branch. It is hence featured in OsmoHLR's Nightly Builds, and will be included in the next OsmoHLR release (upcoming OsmoHLR v1.21).
Distributed GSM is a unique feature set tailored to non-centralized collaboration of communal mobile network sites, as explained in this news post from a few months ago: Distributed GSM / Multicast MS Lookup. Compared to traditional (centralized, highly available) core networks, the most novel aspects of D-GSM are that it allows mobile network sites to roam its subscribers and connect calls without any central entity, and that it minimizes disruption that may be caused by unstable links between sites.
Find full documentation in the OsmoHLR User Manual: there is a new section called "Distributed GSM / Multicast MS Lookup", explaining how to configure and run D-GSM in all detail. Find the latest manuals here.
Please go ahead and give D-GSM a spin, and let us know of any feedback!