RT is still useful when you want to add a comment. For example...
There are exceptions to this, but generally agree RT @natesm Don't use "RT". Use proper retweeting.
I typically see that done like this in my Twitter crowd...
> There are exceptions to this, but generally agree "@natesm Don't use 'RT'. Use proper retweeting."
I see both pretty evenly, I prefer the RT way personally, but both work for sure.
I wondered how to handle native retweeting, given that it doesn't show up as anything other than the original tweet just in a different timeline. I ended up just including "RT" as a convention, but it could probably go in as a section or something.