I really enjoyed this Alfred extension for Alfred 1.x. The extension compares files/folders selected with Alfred in the beautiful Kaleidoscope app. I missed this functionality in Alfred 2 and decided to setup the same file action as an Alfred workflow. If you are interested in it, download and install the workflow below.
Thanks to Jay Freestone, author of the "Stale Coffee" blog, for creating the original extension.
Related: Someone has also created an Alfred workflow to compare items selected in the Finder: http://www.alfredforum.com/topic/1432-compare-finder-items-in-kaleidoscope/?hl=kaleidoscope