Advice about adopting agile development methodology

Agile methodology is good for small projects and for small teams. I don't think they would ever work for constraction projects. But for a Web 2.0 project it can be a great way to get business value product as fast as possible. I can recommend you to read a post about Scrum in marketing, but still it can be useful in your situation. Here's the link http://www.wrike.com/projectmanagement/11/27/2007/Scrum-in-marketing-making-enterprises-adaptive

You can use Agile Methodology to maximizing the team's ability to deliver quickly and respond to emerging requirements. This method is praised for making the team more productive, reducing risks and maximizing the business value of a developed product and minimizing the period of the development time. It does not emphasize on lot of documentation, following whole testing process etc. hence reduces the development time. I think you can use agile development methodology for web 2.0 products till beta version.