Given the parts of the game that take place in http://geck.gamesas.com/index.php/GameMode, I wouldn't 
expect http://geck.gamesas.com/index.php/IsPlayerMovingIntoNewSpace to return 1 during http://geck.gamesas.com/index.php/GameMode.  Have you tried calling it in http://geck.gamesas.com/index.php/MenuMode instead?
If you want to run some code whenever the player changes their current cell, then http://geck.gamesas.com/index.php/IsPlayerMovingIntoNewSpace wouldn't be the way to go about it.
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EDIT:
Is it just me, or are the links in my post not showing up as links?  As usual, I've linked to every the 
GECK Wiki's documentation of each function and blocktype that I've mentioned, but they just look like regular text to me.
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EDIT:
I found the problem, thanks to 
Alleystria.  It turns out I was missing the "http://" from my 
urls.
I guess either the forum now validates 
urls before it decides whether or not to show them, or my web browser has changed how it uses auto-complete.
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