The newest version of Eclipse seems incompatible with the plugin. The plugin as released in 0.16.4 will allow you to add/remove MapReduce servers, and will allow you to browse/manipulate the DFS in the DFS Browser, but will not allow you to run programs. Clicking "Run As * Run On Hadoop" will simply not cause the run-on-hadoop server selection window to appear. No error message is given.
Dropping the 0.17.1 copy of the plugin JAR into the eclipse/plugins/ directory does not fix the issue; it is in fact worse: Eclipse does not seem to regard the 0.17 plugin as real. No "MapReduce Perspective" is made available in the perspectives selection window.