While this is an interesting question, and it would be nice to know, I don't think its the only reason to have these get togethers. For someone like me, it would be more about experience, networking, and fun. I like to code in my spare time, but often work on my own and it kinda detracts from the fun.
Perhaps another interesting question is "Is there anything which differentiates this from a local HackerSpace?". If the goal is to not focus on specific languages or environments, then why not go one step further, and not focus specifically on software?
I understand that there is need to draw the line somewhere, so I don't have any problem with them focusing on just software, however another HN article could be:
HackerSpaces: Over 500 cities strong and counting 
Correct me if I'm wrong, but HackerSpaces are more about the space since you have to store your hardware somewhere and there's more tools involved. With software all you need is a laptop so an OpenHack could maybe migrate around more easily.