JessicaK:
(Side question, prompted by Katie B's latest: why is there a trans-Atlantic difference between humor/humour, color/colour, but it's glamour in both variants?)
As far as I know, the spelling of "-our" words in British English was influenced by French spelling, whilst the efficient Americans dropped the 'u' in these words to simplify, and perhaps to set themselves apart. I hadn't realised 'glamour' was an exception, but perhaps its very meaning was the reason for it keeping its 'u', giving it a hint of European sophistication?