When you think Linux (here specifically Red Hat), you think free. But I was surprised to see just how little of that was "free as in no strings attached". Check out this page (emphasis mine, of course):

The predominant software license is the GNU GPL. Slightly over half of the software is simply licensed using the GPL, and the software packages using the copylefting licenses (the GPL and LGPL), at least in part or as an alternative, accounted for 63% of the code. In all ways, the copylefting licenses (GPL and LGPL) are the dominant licenses in this Linux distribution. In contrast, only 0.2% of the software is public domain.

That's bizarre. I wonder if he considers BSD public domain -- I suppose almost obviously not, though the "strings attached" there are really only "cover the programmers' arses" strings, which aren't strings at all when you've got all the source and you're hacking. Just ask Apple.

Anyhow, an interesting statistic to me.