By being cloud-based, Cloud9 allows developers to work on their applications no matter where they are. Add to that the fact that it is open source, HTML-5 compatible, and free, and you have yourself a very attractive platform that should gain some new users.
The convenience provided by Cloud9 IDE is hard to ignore. Since it can be accessed through a web browser, Cloud9 gives its users the opportunity to develop apps across a wide range of scenarios. It can be used on a desktop in a home or office. It can also be accessed via a laptop or tablet device while on the road. Even better, Cloud9 is accessible through a mobile phone browser as well. Cloud9's cloud-based functionality also eliminates the need for new product licenses if a different employee or partner wants to work on a project, which also saves money.