This could be quite varied, you could be:
- A solo developer looking for a fast/easy way to have a local dev environment that resembles your production environment (say you develop on OS X, but are deploying to an infrastructure running some distribution of Linux. As a bonus, there is also an easy way to deploy to Amazon’s EC2 if you have a solid setup locally.
- A member of a team, where everyone has their own development style and want to avoid the headaches of cross-platform support.
- Someone who normally sets up servers in a third-party hosting environment, but you want to test your deployment without paying a bunch of money in wasted servers (this is where I am!)