In June 2007 virtualization.info reported a news about Invirtus acquistion by Quest, already owning Vizioncore. Nor Quest neither Invirtus ever commented such news.
But a recent move between these companies is indirectly confirming such relationship: Scott Herold, Director of R&D at Vizioncore, popular among VMware users because of its book VMware ESX Server: Advanced Technical Design Guide, left his role to become Vice President of Product Engineering at Invirtus.
This movement is confirmed by new management profile published on Invitus website.
Invirtus hiring of a key Vizioncore representative seems to timely to be casual.