As part of switching to Apache Maven for building CloudStack, the .classpath and .project files used by Eclipse were removed. This page describes how to get CloudStack loaded into an Eclipse workspace.
These steps have been tested with Eclipse Indigo - it's suggested you use that or a newer build.
To minimize confusion, start with a clean workspace with no other projects.
This wiki page shows how to install the Maven integration for Eclipse plugin. (For those using Yoxos, just search for M2E and add it to your Eclipse build)
After installing the plugin, restart Eclipse.
Now you can import CloudStack using the M2E plugin:
Eclipse will import the projects and build the code. At this point you should be able to develop and debug code as usual within Eclipse.
One bonus of the Maven integration is it is now easy to run and debug the CloudStack UI through Eclipse:
Maven will download everything needed to run CloudStack with Jetty, build the code, and run the UI. You can connect to it via http://localhost:8080/client.