I just discovered that letter-spacing doesn't always work in webkit (and perhaps other browsers?) when embedding fonts. I've tried it on two different fonts and received different results.

"League Gothic Regular" will work

<http://www.theleagueofmoveabletype.com/fonts/7-league-gothic>

"Quicksand Light" will not

<http://www.fontsquirrel.com/fonts/Quicksand>

What's the skinny? Is there a way to force the hand of non-compliant fonts?

Quick note: Firefox does seem to apply to both fonts.