Hi Nikki;
My understanding of the Long Count calendar is that it is a count of days since the "creation date" in their culture. Much like our Gregorian calendar, it does not have an 'end'. If I say something that references "the year 20384", you can work out that I'm talking about a date about 18,000 years from now.
The Maya had a more elaborate counting system, which used base 20 (instead of our base 10). Their calendar reflects this in that most of the units of time are a factor of twenty larger than the prior unit. The base unit of their calendar was the "K'in", which represents one day. The next unit was the "winal" which represents 20 days. In one of the exceptions to the 20 rule, the next unit was the "tun" which represents 18 winal, or 360 days. The next unit was the "k'atun" which is 20 tuns or 7200 days (almost 20 years). Then comes the "bak'tun" which was 20 k'atuns, or 144,000 days, which is about 394.25 years.
This is the unit which (according to the 2012ers) comes to an end in 2012. But wait, there's a problem! In 2012, (if the currently accepted correlation between their calendar and ours is true) the current bak'tun count rolls over from the current number (12). Some people think that this means it will reset to zero, but most modern scholars think that it continues to count up until it reaches 19, and then rolls over to zero. In either case what happens is that the bak'tun count rolls over to zero, and the next higher "digit" (if you will) increments by one.
In our base 10 counting system, the equivalent would be looking at the 'places' in a large number. So in our current year (2010) there is a 'thousands' place, which contains a 2, a 'hundreds' place which contains a zero, a 'tens' place which contains a 1, and a 'ones' place which contains a zero. Last year the 'ones' place was nine, and then when we started this year, the ones place rolled over to a zero and the tens place incremented by one.
Yes, there are higher cycles in the Mayan long-count calendar. This is something that the 2012ers ignore. In most cases the inscriptions ignore the higher cycles, in a very similar way to how we write "'10" instead of '2010'.
The next cycle above the bak'tun is the piktun, which is either 13 bak'tuns or 20 (and most modern scholars seem to be leaning toward the 20 number), which would put the "end" of the current cycle another 2760 years into the future. But, even if they did cycle the bak'tun at 13, this is still irrelevant, because there are cycles (or places, if you will) above the bak'tun.
1 piktun is either 13 or 20 baktuns (around 7885 years). 1 kalabtun is 20 piktuns, or 157,700 years. 1 kinchiltun is 20 kalabtuns, or a bit over 3 million years, and the highest 'named' unit we know of is the alawtun which is about 63 million years.
So, hopefully you can see that the idea that the long count calendar 'ends' in 2012 is a ridiculous statement.