@Susan. Good points. I think that unexplained mysteries like these open the table up for speculation, which can sometimes be fun.
Just as Silicon Valley is almost synonimous with IT, so is Wall Street with finance. In theory, Wall Street would be Silicon Valley's biggest customer base.
I wonder if things can be explained by a difference in corporate culture. In nyc, I've often heard that companies do not want to pay to train someone else's future employee. Also, an overwhelming majority of IT jobs at major corporations in nyc tend to only be available as temp/subcontractor positions. I'm willing to bet that most IT Outsourcing companies either cannot afford to send their employees to events like these, or they cannot afford to have some of their top employees leave for any extended period of time.