I'm in SF for the weekend from Austin. What's going on this weekend. I checked Startup Digest (which is great for Austin thanks to Joshua Baer) for Silicon Valley and couldn't find anything. I also checked this Quora post: http://www.quora.com/What-are-the-best-startup-networking-events-meetups-in-San-Francisco. I'd like to get a sense of what the scene is like.