This is an excellent idea! I see this a lot more lately and I prefer to work on different projects to keep my talents fresh as someone else mentioned. I also like working in different environments because as you mentioned, it is difficult to get a feel for a team in just 4 hours. In the traditional job environment, you often find that the team isn't a fit until its too late. Your arrangement is great for all parties. However, the employer doesn't have a lot of incentive to invest in part-timers or moonlighters and there is less of an incentive on the employee to make the start up their life as is necessary in a lean and young company.
