What functions were released on 2011-06-23? 
CREATE TABLE "zune_hd_applications" (
  "title" text,
  "developer" text,
  "category" text,
  "function" text,
  "release_date" text,
  "version" text
);
SELECT "function" FROM "zune_hd_applications" WHERE "release_date"='2011-06-23';