Kick-off meetings would fill a specific purpose in bringing team members together and get everyone on the same page. It will allow everyone to see from the start who is on the team and allow them to begin to forge interpersonal relationships and even start organizing thoughts on their own before they begin their stages of the project. It can also be a good motivator for individuals to help them realize the project is both real and started. There can often be doubt among individuals and rumors spread so easily that people may not believe a project will be brought to fruition until they actually see it happen.
Tech Republic (http://techrepublic.com.com/5100-10878_11-1038766.html) has a great article on planning an effective kickoff meeting. The takeaways from the article include establishing expectations, communication plans, a timeline of the project, and the details of the project itself. This will allow the team to see the project manager is taking action and authority of the project and will also allow them a potential opportunity to provide immediate feedback on the planning of the project. This article does a very good job of helping the reader understand the importance of a kickoff meeting.
I think one of the most important things for this meeting are the things that may not be related to the project at all. The psychological impact of the meeting can help the project start out on the right track. If all of the team members see the PM put together a well-organized, well-planned meeting, it will set the tone for the project. The TenStep.com (http://www.tenstep.com/basicI/21.0ProjectKickoffMeeting.htm) approach also states that the meeting should include team members, stakeholders, and the client (if it exists) should be part of the meeting, netting the same results from the previous benefits listed.
There are four things that all projects have measured in some way or another: what will we try to accomplish, how long will it take,...