Ok, than it's not just me
Since I wanted the native app I did a little digging these days, and found a Droid GSM Dump, from which I extracted the 'facebook.apk' . I'm gonna give some simple instructions if someone is interested in installing this app.
1. Download the facebook app from here (800 kb) .
2. Transfer the app to your SD-Card (I put it in downloads)
3. Unmount, and navigate with a file-manager (I used Astro) to the file and click on "Open App Manager"
4. Install the file and have fun
A few infos on the app :
+ Name : com.facebook.katana
+ Version : 1.1.0
+ Syncing contacts doesn't work fully (cross checked that with another forum)
I'll update this if I find sth new...