An "Under Construction" page is a waste. Nobody wants to follow a link, only to find nothing there. Even worse, if the UnderConstruction area takes longer to build than expected (gee, that never happens, does it?), users may be led to believe the site is no longer being updated.
If a page isn't ready for release, you may want to mention it, but Don't provide links, don't provide menu items, or any navigation at all to areas that will not prove useful or informative.
See also:
http://www.graphics.cornell.edu/~gordon/atwork/ http://www.acme.com/jef/construction/ http://boulter.com/construction/one.html http://www.iconarchive.com/construction/ http://www.donotenter.com/cool/ucgraphics/ http://www.indomaffia.tk http://www.indomaffia.info http://www.pepelka.nl http://www.warayut.tkWhat are you, the Andy Rooney of software? It's not always practical to update every part of an entire web app(s) when linked items are finally finished. You are assuming idealized tools.