The change from python 2.6 to 3.3 would probably affect some plugins, so one could reason that, by adding the "3.0" tag, plugin creators would more easily accept the need for porting.

Underpants could be a synonym for underwear, in which case it could make sense: you'd like to keep you fingerprint private on the web, and your underwear private in real life.

This is exactly how I took it.

Would there be any possibility for the addition of native Long numbers to JavaScript, or is this, due to some nature of the language, something that can't, or shouldn't, be included?

I'd settle for integers. :)

You could add a 64-bit int type, sure, but since implementations use pointer-sized data that has to represent other types as well, making it as efficient as a long long in C isn't as easy. Seems unlikely to muster enough priority. (I haven't been following their work, though.)

64-bit bitwise operations would be a big help.