Onya cobber :)
The main reason that No Chill became popular in Australia was because there are a number of local companies that do "fresh wort kits" - 20L of wort from the kettle with a long shelf life. Not the cheapest at around $A45 a pop but still less than half the price of commercial beer and usually great beer, foolproof.
Each kit is really just a no chill cube so the precedent was there. Also there was many a brewer who went on to all grain and what are you going to do with all those feckin cubes????
Anyway on topic, I did a Russian Imperial Stout in October 2011 and for various reasons like lack of fermenters, moving house interstate etc it didn't get pitched till a month ago. Was perfect.
Until then it got used to hold up a shelf, as a doorstop etc :shock: and eventually out of sheer guilt I pitched it with Wyeast Irish Ale yeast and it's now in a keg maturing for a few months (I'll enter it in a competition). It looked pretty sad after its ordeal.
Generally though I pitch within a few days because, on the flipside of the coin, I've had a couple of cubes that did get infected... only takes one wild yeast I suppose. So fanatical sanitation and highest temperature are a must. Also I don't normally use a tap, this was the only cube I had spare at the time.
Edit: I just saw that the OP mentioned unboiled wort. Asking for trouble, would probably be fermenting nicely by itself after a couple of days, grain is full of microorganisms, many of which would survive mash temperatures.