A simple question: what is the purpose the the “dimple” often found in the bottom of wine bottles?
To make it look like you’re getting more wine than you really are. 
I think that may actually be it, no fooling…
I always thought the aim was to make the bottle more stable when standing on the “punt” end.
Sure, because a 750ml bottle with a punt holds less than a 750ml bottle without a punt.
It’s also called a kick or a kick up, and Cecil’s answer is correct (of course.)
It might have served a purpose at one time, but today is really just a marketing decision.
Most people expect a higher end wine to be in a bottle with a punt, so most winemakers put their better wines in a bottle with one. It’s not needed and serves no real purpose for still wine bottles. Take a look at any cheaper wine’s bottle (Two Buck Chuck is a perfect example.) The bottom is about as flat as a pancake.
How’d it end up being called a punt?
That usually refers to a A flat-bottomed boat with square ends; from which one may fire a Punt gun.
punt ( P ) Pronunciation Key (pnt)
n.
The indentation in the bottom of a champagne or wine bottle.
[Perhaps from punty, iron rod used in glass blowing, probably from French pontil, from pointe, point, from Old French. See point.]
From Dictionary.com
An additional question not coverered in Cecil’s response:
Concerning bottles of sparkling wine (like Champagne), I had heard that the punt helped strengthen the bottle to prevent bursting from the pressure of the bubbly.
True? False? Irrelevent?
Some googling brought up these links,
http://www.oakstone-winery.com/oakarticlesold.htm#15 (scroll down a bit for the paragraph on punts): mentions that it was solely a result of hand-blowing manufacturing processes, and was retained for the “classiness”.
http://cheers.libsyn.com/index.php?post_id=2297 : indicates that the punt did originally provide some stability against bursting, but it’s not technically required for modern glass.
I’ve heard it called a ‘kick’
In addition to the above, waiters use it as a grip to reach across the table when filling your glass.