It depends. I could see myself doing this as a side gig in the future if it's managed well and the price is right. That's really the rub: my current job at a major tech company pays great, if Gigster's hourly rate is significantly less than what I already make then it won't be worth it.
On the contrary, I'm considered a 'good' developer by the normal standards (education / company / title / projects / etc.) and I would consider moonlighting. I usually work another 40-50 hours a week outside of professional employment on my own projects, so doing an app or website for some extra cash once and a while isn't a stretch. I applied.
Gigster was actually designed from the freelancer's perspective first - no bidding, no interfacing with customers all specs are in a standard format, reliable/regular payments, etc. I don't know of a better place to freelance.
I'm really struggling to believe "elite" people from MIT or google are going to be working at a rate where they can make 10-20k per month. It just doesn't really make sense given their other options.