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
It seems to me that this is caused only by svg fonts!!! I wasn't able to verify it strictly but my test cases prove that much.
Reorder your font-face urls putting svg format last, it should fix the problem. But svg fonts won't get used and rendering might be dirty(er)