Opportunistic entrepreneurs jumped onto the Web 2.0 bandwagon pretty sharpish. One such group were the developers who took advantage of the phenomenal growth of Facebook, by building their own applications for the social networking giant.

However, a nasty surprise could be waiting round the corner for several developers currently working on applications for Facebook. The site is reportedly about to introduce a feature that will allow users to group their list of friends into more organised groups or categories.

The problem is, there are quite a few start-ups currently working on applications with that exact purpose, and their work, not to mention business concepts, could be rendered completely useless.

The site, which has an average 3% weekly growth rate, was opened up to external applications in May proving popular with developers around the globe, giving them direct access to 43m active users.

So far, more than 3,000 applications have been built on Facebook Platform, which enables developers and engineers to integrate with the site, and 100 new ones are added every day.

One of, if not the most, popular of these applications is Top Friends, which allows users to highlight their best friends for quick access. However, the new feature currently being developed by Facebook, described as ‘in the works’, could eliminate the need for Top Friends altogether.

Staying ahead of the game can clearly prove lucrative in any industry, but in the Web 2.0 era it’s more important than ever. There’s a few developers out there scrapping their ideas as I write, but let’s face it, they’ll be on to a new money-spinning idea before founder Mark Zuckerberg can say ‘RIP MySpace’.