Wow, this thread is really something.
I attended my SIL's wedding last year and as parents we refrained from dressing my daughter in what is technically a bridesmaid's dress (or marketed as such) but could also simply be a nice party dress, just in case anybody recognised it as having been marketed as a bridesmaid's dress and thought we were trying to somehow "big her up" or make her look like she was part of the bridal party. This would not have been the case in retrospect as the bridesmaids were dressed in a tealy aqua colour.
Its amusing and interesting that a lot of the vitrol surrounding this issue is directed at women, whether its those doing it or those objecting to it.
"YANBU. It is very rude, and stinks of a mother thinking her pfb should be the centre of attention even at someone else's wedding" - from Freddo's post on page one - is it only a mother who would do this, then? Or is it the kind of faux pass a father is also likely to make? Or do father's never have any say in the getting-dressed of their daughters? And if not, why not? 
As for all the bridezilla comments - is it only the bride who might be annoyed if this happened? Or is the groom allowed to be outraged on behalf of any female guests who also aren't bridesmaids?
Everyone is sounding like a bunch of loons TBH.