I have installed DTP 2.0 (on an Intel MB late 2008 running 10.5.6) and noticed a recurrent warning message each time I launch the app.
The message mentions “DTP is an app downloaded from Internet. Are you sure you want to open it? - Display the Web page or Cancel or Open”.
This message is quite standard for apps downloaded from Internet but, usually, it appears the very first time the app is launched but no longer the times after.
With DTP 2.0, I get the message systematically while I get it only once with the other apps.
I do not know whether this comes from the beta DTP or from specific settings of OS X which would be wrong in my configuration.
Any support is welcome.