Facebook’s Android app is the most popular app in the Android Market across several age groups … aside from the Android Market app itself. That’s according to new research out today from Nielsen that reports on the percentage of Android owners that have used an app during the month of September.

Facebook’s app hit 80% penetration in both the 18-24 and 25-34 age groups, and was only slightly less among 35-44 year old users, with 77% usage. Those numbers are higher than all other non-Market apps, including Google search, YouTube, Gmail and … gasp! … even Angry Birds.

Here’s a look at Nielsen’s overall Android app usage statistics:

Angry Birds did score the top usage rate among game apps in the 25-34 and 35-44 age groups, while Words With Friends nudged it out in the 18-24 crowd.

The Pandora Radio app has some interesting usage stats, with a high of 30% penetration among 18-24 year olds, then declining to 28% and 20% in the successive age groups.

Not shown in the chart above is Google Plus. Nielsen says that app is more popular among users 25 and older, but it wasn’t strong enough to crack the Top 15 in any age group.