Congratulations;  SL 6 beta runs so flawless on my two machines that I'm 
getting bored.  I'm waiting for something to bork soon so I can start 
googling for fixes.  Until then:

The only issue I can find is when the "rings" plymouth boot screen is 
displayed, the words "Scientific Linux 6" look like they were rendered 
on a Nintendo; especially when contrasted with the smooth animation just 
below it.

The "offending" file is located at 
/usr/share/plymouth/themes/rings/header_image.png.  I've created a 
smoother looking png; but just replacing the original file has no effect 
at boot time.  I suppose the animation is rendered beforehand somehow 
and just played back at boot.  I'll look into it.

If you'd like a smoother-looking png file, I'd be glad to share mine.  
I'm not a graphic artist or anything, but gimp is easy enough.

In all honesty, thanks for the great work.  I'm just a stay-at-home-dad 
with an ME degree and an addiction to linux; but you're saving me a 
couple hundred dollars a year with your efforts;  money better spent on 
books for my three girls.

Chris