The LinkedIn Flex Developers Group is full! Apparently, LinkedIn groups can have 3000 members, and that's how many the group now has. I have over 50 requests to join pending approval, and can't approve them. I have pinged LinkedIn Customer Services to ask if there is a way to raise that limit, but for now, I can't approve any more requests, sorry. If the limit gets raised, I'll let you know (and will approve those in the queue).
