You can now browse the App Store directly from within Facebook via Apple's newest Facebook application. There are a few tabs to chose from; the proverbial Wall and Info, but then it starts to get interesting.
You have a Featured tab that shows you the week's spotlighted applications. A Games tab lets you filter by any game genre. Search and Share, of course, lets you search for any app. Once you find the application you are looking for, you can launch into iTunes Preview and straight into the iTunes Store to get it (and post it to your profile, of course).
The latter is what I am excited about because now I can share my recent app favorites with them.
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