This is cool. So I can program mobile with my usb. What makes such a big difference between the standalone and the normal version that it takes weeks to bring it on the same stage?

We have written a new launcher for the USB version, to improve reliability, which took some development effort. Also, in general, this was a fairly low-priority task considering all the things the team does. On the positive side, for future versions, we should be able to put out the USB version at more-or-less the same time as the regular release. However, I'm not sure what you mean by "program mobile". This is standard Greenfoot, it won't do mobile apps.

Greenfoot launcher gives message: Greenfoot could not find any Java system: A JDK/J2SDK must be installed to run BlueJ. I thought the JDK was included in the download for the stand-alone version. What did I do wrong?

Apologies, but the download included the wrong version of Greenfoot - this has been remedied now. Anyone who downloaded it previously may wish to do so again. danpost, the file must be unzipped at the "root" level of a USB stick. It won't work correctly if you unzip it into a folder. This is something we might be able to remedy in the future.

Is there a reason that for testing, I am limited to only 5 strings per user, instead of 10? I am getting ArrayIndexOutOfBounds: 5 with

From Class UserInfo API documentation: The data that can be stored for each user consists of a score, 10 additional general purpose integers, and 10 strings (limited to 50 characters in length). In addition, the user name and user's image can be retrieved from the user data.

Ah, that's a mistake; it should say 5 strings! The documentation for the setString() and getString() methods is more accurate, specifying that there are NUM_STRING storable strings (NUM_STRINGS is defined as equal to 5).