--version is standard, so it stays.

version is preferred, as it's actually a command, so it stays too.

'hg --version' definitely has to stay, just like 'hg --help'. Removing 'hg
version' from 'hg (help|--help)' might be an option, but I think this should
only be done if other commands should be hidden from normal help, e.g. because
they've been replaced by options to other commands.

Anand Kumria mentioned on the list that something like "hg log --version" should
be disallowed, but other tools (just try 'ls -la --version /foo') behave the
same and I consider this a good thing.

It is very common practice to use 'prog --version' to look at the
version of a program. Mercurial can do it with 'hg version' but it
is less standard. I would prefer that the '--version' option remains.

   Vincent

there's already a 'version' command.