This is probably one for John to answer.
Currectly U3 Offers a prototyper to convert an application into a u3p file. I noticed that John has released the 3 Mozilla apps as U3 apps so far, but wouldn't most of the applications here already conform to the U3 guidelines? I have been talking to the U3 consortium about the guidelines and so far I havn't found one that most of these apps do not meet. I would love to ee the same volume of applications here on portable apps up on software central on the U3 site. Just a thought, let me know what you guys think.
Please read here.
A simple search of this site for "u3 versions" shows that thread as well as many other times this has been mention about one app or another...