[Mediawiki-l] Same text at the top of all Talk pages

[FxParlant]

Hello,

I'd like to have a small text in all the pages from the same 
namespace(Talk:).
What I mean is like the "fund raising" text from mediawiki(not 
editable)... but only in for a distinct namespace pages. Is there a 
template somewhere for each namespace that I can hack?

Thanks
François