For eons people have complained that "Put the text of the new page here." is extremely unhelpful and promotes confusion among newbies to wiki; that it discourages people from doing anything further with the site as they don't know what they've stumbled into; and that it encourages a lot of useless blank, "Put the text of the new page here", and "What does this do? FJSDIOJDFS" pages. Longer, more informative messages have been suggested.
As an experiment, I've gone ahead and changed the (English) message to the following:
You've followed a link to a page that doesn't exist yet. If you'd like to create a new page under this title, delete this message and get typing! Click the 'Help' link up top if you haven't used a Wiki before and aren't sure how to go about it.
If you didn't mean to create a new page, just click the 'back' button in your browser, or use the search box at the top of the screen to find existing articles.
Suggestions for more consice, professional, friendly, and informative wording are welcome.
-- brion vibber (brion @ pobox.com)