Update: It seems this bug has been fixed on most systems by now.Blippo-Heavy.ttf had a problem on my unix system. This has since been fixed. Conceivably this problem could actually have been with the true-type rendering engine, or the conversion used for the font (there's a string in the font file that claims "®Converted by ALLTYP") I don't know enough about font files to know where the problem lies. But on my ubuntu system (feisty fawn) I'm getting kerning problems with Blippo-Heavy and specific character combinations for font sizes of 20 or higher. I see this problem in firefox and in gimp (though admittedly not in gnome-font-viewer). I've seen the problem with the 'te' and 'is' combinations, though it probably exists with others. Feel free to do an exhaustive search. Unless your blippo has been fixed, then these have large gaps between the letters (incorrect kerning?):
Unfortunately this fix doesn't seem to be working anymore. The bug used to exist with all font sizes, and the <nosp> trick used to work, but now it's only for font sizes 20px and higher, and nosp doesn't work. Urgh.