A little bit late to the party but I wanted to explain that haka that was linked further up the page.
Originally doing the haka prior to the game was to signify the importance of Maori culture within New Zealand, and the haka that was performed was the same haka that was done by the North Island Maori before a major battle with the Maori of the South Island.

It's purpose has been eschewed a bit since then, so much so that the new haka they do (that in the above video) is very much just a piece of propaganda for the New Zealand Rugby Union (you can see the translations on the wiki page here).

Regarding the freezing in place of the opponent during the haka; opinions differ both here and abroad as to what the best reaction to it is. Some believe that doing anything other than walking away is disrespectful, while some players themselves believe the only way to not let it psych you out is to stare it in the face.
A great example of this was a match against wales (Video can be found on YouTube or see below) where there was something of a stand-off after the haka, as neither team wanted to be the first to move.