I don't believe ever in shared office spaces. Peter talks a little bit about this, every good startup is a cult. It's very hard to create a cult if you're sharing space with people.
Keith RaboisBarrels are very difficult to find. But when you have them, give them lots of equity. Promote them, take them to dinner every week, because they are virtually irreplaceable because they are also very culturally specific. So a barrel at one company may not be a barrel at another company. One of the ways, the definition of a barrel is, they can take an idea from conception and take it all the way to shipping and bring people with them.
Keith Rabois