When attempting to install the Maven plugin for Eclipse (m2eclipse) from the following location…

http://download.eclipse.org/technology/m2e/releases

…I was encountering the following error:

Missing requirement: Maven Integration for Eclipse (Editors) 1.2.0.20120903-1050 (org.eclipse.m2e.editor 1.2.0.20120903-1050) requires 'bundle org.eclipse.wst.sse.core 0.0.0' but it could not be found

To solve this, return to the Install New Software window and add http://download.eclipse.org/releases/indigo as a software site.

At this point, you should now be able to install the Maven plugin at the next attempt.