With over 10,000 applications in the App Store, it’s getting harder and harder for developers to get their app noticed. Clearly, the name of the game is to get your application among the Top Paid Apps list. Making the list is not enough and many are looking for new ways to get you to their application. Developers are now using their icons to promote discounts or accomplishments. One fifth of the Top Paid apps now contain promotional language such "On Sale" or "Game of the Year".
The discounted apps do stand out and probably having a positive impact on sales for the developers. You can expect other developers will catch on and you’ll have more apps with some sort of promotional language on their store icons than not. Eventually, it will lose it’s intended affect and just contribute the App Store looking more like a Discount Store.