Re: There is a scary discussion on the Ubuntu Developers mail list.
Pretty much everything has already been said in this thread, so I'll just recommend that you go back and read through all of it.
Originally Posted by James85
This all stems from a developer discussion that was looking at what may be necessary in the future if and when Ubuntu gains a sizable share of the desktop market. There are no known viruses in the wild for Linux right now, and there are relatively few threats if you practice common sense safe surfing.
The discussion, moreover, was about adding new features that would make it even easier than it currently is to install software, and how to implement this without greatly increasing the risk for users who don't spend a lot of time reading security bulletins.
That's my summary, but don't take my word for: read it yourself.