Even casual games are taking a page from the book of online worlds. Casual title Diner Dash, which charges players with pleasing restaurant patrons in the food service rush, has incorporated some social networking features, as well as some personalization elements into the game -- and it's also added microtransactions.

PlayFirst chose the latest title in the franchise, Diner Dash: Hometown Hero as the new business model's proving ground, letting players dress up their waiter and customize their restaurant with virtual goods, and new multiplayer modes let them show off the goods they've earned to their friends.

According to a spokesperson from PlayFirst, more than 20 percent of all purchases within the game can be attributed to sales of virtual items and level packs. Diner Dash: Hometown Hero offers a free trial of the first seven levels, but players pay a one-time fee to purchase the game and access the full version.

Other areas of gaming are learning a lot from the success of virtual worlds, and the microtransactions business model is providing a useful alternative to the casual games space, which is still largely in an experimental phase in terms of discovering the most effective ways to monetize its content.