If you take a look at your App Store settings, you'll find some new options for Automatic Downloads. This new feature allows you have new purchases made on other devices automatically download to the device you're accessing the settings from.
For example, let's say I purchase 1password Pro, a universal application for iPhone and iPad on my iPhone. If I have Automatic Downloads for apps enable on my iPad, 1Password Pro will automatically download to my iPad over the air. This feature is available for music, apps, and book purchases.
For those of you who may be concerned about how much data this may be using, turn the "Cellular" setting to OFF so that purchases are only automatically downloaded when connected to Wi-Fi.
Personally, I will have options set to ON on my iPhone, but apps set to OFF on my iPad. I do not want iPhone apps installed on my iPad; if I purchase a universal application, I'll download it manually to my iPad. What about you? Do you plan to enable Automatic Downloads? And if so, for which combinations of music, apps, books?