-- have stopped working on my machine in all browsers, but seemingly just for me.
They stopped working several weeks ago -- long ago enough that if there was one thing I did on my laptop to cause this, I fail to remember what it was.
I use a variant of Firefox called Pale Moon
that they keep running parallel to Firefox's upkeep; like Firefox, it's currently on v3.6.15.
I have tried it both in Pale Moon and Pale Moon Safe Mode, as well as MSIE (8.0.7600.16385) and Google Chrome.
It doesn't work in any of them: the keywords don't work in Firefox, and MSIE and Chrome don't respond to the "+googleCal" links.
(pb was kind enough to work with me to confirm that it does appear to just be me -- thus the reason why I didn't MeTa this.)
I imagine if it is something present in all browsers, it's something on a deeper, machine level, but I'm new enough to Windows (began using it instead of Mac OS X midway last year) that I don't know what to look fir as a possible culprit or contributing factor.