Apple announced last week that it would begin offering volume purchasing for iOS apps, and a week later the program is open for enrollment (but still U.S.-only, unfortunately). Enrolling in the program requires that you be authorized to make purchases for your company, and you’ll also need a valid D-U-N-S number.
Volume purchasing allows businesses an alternative to the App Store for bulk purchases of iOS apps. All paid apps in the App Store are available through the program, at the same price as that listed in the App Store. Note that Apple’s guide to the program doesn’t mention anything about discounts for bulk app purchases, so purchasing Keynote for all 50 of your employees is going to run you close to US$500.