As a student of music production, I can tell you WHO is doing the 'auto-tuning'... It's the producers and/or the mix engineers.
I have heard from professional producers that vocal tuning manipulation has been done with artists even as talented as Whitney Houston.
Usually, the pitch correction is very subtle, but I have noticed it on the radio on almost every song lately. (I'm not talking about the whacked out 'Cher' or even more crazy 'Lil-Wayne' effect, just some subtle help here and there to get rid of a little 'pitchiness')
Once, one of my instructors laughed at how 'terrible' Fergie was as a singer. He noted that on a Pro Tools instructional class where an original Fergie recording session file was used, the voice was 'horribly' out of tune! Of course, this particular instructor had a weird form of perfect pitch that prevented him from enjoying almost anything more than a few cents out of tune... but still...
Oh, and I guess my point is that there are in fact more people doing this than you might think... including plenty of indies! It's not just a corporate overlord thing... I myself use Logic Pro which has a pitch correction plug-in. I have used the plug-in plenty of times and I am not working for any major label. (I like to think I use moderation however)
Almost everybody who owns a studio or a DAW also has some sort of auto-tuning software (not necessarily Antares Auto-Tune). In fact, everybody who has GarageBand 2 or higher on their mac has pitch correction available pre-installed. It isn't as powerful as Auto-Tune, but it gets the job done if you want to sound like t-payne.
Anyway, if you think Auto-Tune is cool, you should check out the video on Celemony's
Melodyne. Besides pitch correction, the software has a feature called Direct Note Access which lets you extract individual notes out of a sound file and correct them or even create completely new chords. You should also check out the guy's beard. That's what I call an Audio Engineer!