UPDATED: Batch Export Playlists v1.4
iTunes can only export a single playlist at a time using the File > Library > Export Playlist... command. My mouse finger's inter-phalangeals are achy just thinking about exporting more than a few that way. Batch Export Playlists v1.4 will export each selected plain, Smart, and Genius playlist as individual XML or M3U files to a user selected directory. Such files can be re-imported into iTunes again later or into other devices or apps.
As a bonus, Smart playlist XML files can be exported as two files, with one containing just the Smart criteria.
This latest version adds a heirarchical view for Playlist Folders which more closely emulates iTunes' playlist view and has some minor tweaks for better compatibility with OS X 10.10 and iTunes 12.
More information and download is here.