Sounds like there are a lot of fevered egos on both sides of the debate.
Personally, I like colons. I'm sure if python forbade them, I'd stop using it. That said, the folks on the other side seem to have a good argument in that "semicolons are optional; [sic] why aren't colons?"
I don't at all agree with the people calling them line noise or saying that they hurt readability (seriously, what?), but it seems sensible to allow the option. After all, if you have to read someone's code, there's a decent chance that you can use a style guide to force them to use colons. It's also probably not hard to hack the parser to create a tool that simply adds or removes colons to or from old code to make it conform to a new style guide, if this were necessary.
In short, the idiots that are against colons might be idiots, but at least they seem to be more fair.
-- Cheers, Leif