TZ> Should the link be in the manual? Should the manual freeze this
TZ> information? I can see both sides of the argument but it seems that
TZ> freezing the information *and* providing the URL would be technically
TZ> best but also most confusing to the user.

Ping? I'd like some opinions please. This is about how the Gnus manual
coexists with emacswiki.org and similar sites, not just about GMail, so
I don't want to make the decision on my own.

What's particular about the situation with GMail is that the manual would be freezing documentation about something other than Gnus. If GMail changed (and it does change quite frequently -- it's still in beta after all...) then the documentation would be wrong. Not just out of date like documentation for september Gnus or quassia Gnus is -- that documentation is still accurate as far as it describes those versions -- it would be incorrect even about the same version it was written for.