That will get you your 5 minutes^H^H^H^H seconds of internetfame already. However, it will only create a short popularity spike and you constantly have to invest in promotions to keep that up.
The blogpost doesn't tell you to put ads for your other apps into your apps (that would be stupid!), but to think of ways in which they can complement each other. That way you get effortless crosspromotion, can touch vastly different traffic sources and channel users to your main app.