For the time I was working there I'm quite sure most of the tools were internally made by MS: - they had their own map reduce - they had their own service deplo

For the time I was working there I'm quite sure most of the tools were internally made by MS: - they had their own map reduce - they had their own service deployment and management system - their own db and nosql - etc... about the search and relevance they are updated quite fast, sometimes with big code replacement. This means that even if powerset tech was used as a start (and I do think it was not, it was possibly adapted and integrated -- i believe the base code was msn/live) it is now changed in most of its pieces.