Hey guys,
I just saw the
BitcoinTalk.org Forum App in the Google Play Store...
so I downloaded the on my smartphone.
I could log me into my account here but I think the app is not very good so let's start the developement of a better BitcoinTalk app!

Best regards,
Patrick

I think people should not spend time and effort to make a mobile app since it requires too much work and still will not be stable because there isn't a good API to scrap data as achow101 said.