MP4 versus MP3 - iTunes SONG QUALITY??

I've never seen a "+" sign next to a track.

Then you're not buying tracks carried by EMI or one of those few independent labels that have allowed Apple to sell as Plus.

And why does higher quality and higher license have to go hand in hand.

I don't know what you mean by "higher license".

The Plus songs have no DRM. They are still under copyright, so you can't legally duplicate them and distribute them, but there is nothing built into the files to prevent you from doing so. Regular iTunes songs have a number of restrictions: you can only install them on a certain number of machines, you can't burn a particular playlist of them more than a few times, you can't play them on a machine you haven't authorized, etc.

Not all songs are in Plus format because not all record companies are yet convinced that people won't copy and distribute the files if they aren't technologically prevent from doing so.

Why don't they have the all at the 256?

Because most record companies will not license them for sale at that rate. Why they won't is anyone's guess, but most probably they want to sell you the entire CD rather than just a couple of tracks, so they force people to buy the CDs if they want top quality.

Is there a limit on how many times you can burn or export them or something?

For tracks on the iTunes Store that are copy-protected, you can burn a given playlist with such a purchased track to an audio CD seven times. After that you have to make some sort of change to the playlist to get further burns. There is no limit on the number of times you can burn a copy-protected track to a data disk for backup. Copy-protected tracks cannot be exported to any other format.

iTunes Plus tracks have no technological limit on the number of times they can be burned or exported.

+"Why don't they have the all at the 256?"+

At amazon.com, all the tracks are at 256. Many of the songs sold in the iTunes store at 128 with DRM are available at 256 with NO DRM at amazon.com. Yes, same song, same artist, same album.

Actually, Jeremy, I'm 98% certain that I read that the iT Plus tracks have identification encrypted into the file when they're purchased as to who purchased them. Based on that, it would not be a bright idea to get on your favorite P2P service & post those iT Plus tracks for download. You can be identified.

iT Plus tracks have identification encrypted into the file when they're purchased as to who purchased them

Yes it does.
Get info on an iTunes Plus song.
It has you first and last name, the iTunes account used to purchase it adn teh date & time it was purchased.
This is all part of the song file itself.

Thanks, Chris, for confirming what I already knew.