And kerning has _always_ worked for me, ever since Fred switched us to using Pango in version 0.39. I even wrote about it in the release notes:
OK, I was looking in the wrong place in the Pango sources. It looks as though that kerning function does get called automatically in all releases 1.11.0 and earlier, but not in 1.11.1 and later. The reason why this change was made is very unclear because it's part of a larger checkin, but it does look as though it was done on purpose. See revision 1.21 of pango/modules/basic/basic-fc.c.
As far as I can gather, the simple freetype kerning has been replaced by the opentype pango_ot_ruleset_position() function, which has an entry in the documentation but no explanation as to what it does. It'll be something complicated related to the GPOS opentype table and probably liable to breakage.
In summary then, I now think this is a Pango bug and should be reported to them.
So, something very strange is happening. If you say that to enable kerning for everyone is a matter of a single call, then please add this call :) Ideally it should be conditional on the 'kerning' CSS property, but lacking that, I think "always on" is better than "always off".
I would have done, except I simplified a little. It's one call on Linux, and a great deal of hacking around on Windows.
R.