We take for granted this period of time in late-summer and early-fall that we call "Oktoberfest"; or, as the Americans call it "Octoberfest." During this time breweries are releasing a style of beer called an "Ok(c)toberfest" or even just "fest." There are beer fests held, often under the name Oktoberfest Celebration. It seems to be a celebration of Germanic Heritage, or at least there appears to be relation to German culture and heritage.
The question seems to be, what are we celebrating? While Oktoberfest initially held a very specific meaning, I think now it serves to celebrate two things: 1) Germanic heritage and culture and all of the great contributions that Germans have made to world history and culture; 2) fall harvest.
These harvest times have always and inextricably been linked with beer. It just so happens that if you harvest grain, malt it, brew a beer and let it age for a period, it just so happens to be ready by the planting period the next Spring Hence, we get Maibocks and other hearty early-spring releases. If you harvest early grain (winter grains), malt it, roast it a bit to develop flavors, use yeasts that can tolerate slightly warmer temperatures, and throw it in a dark cool basement for a few weeks, it is ready right around the fall harvest. Hence we get marzens (German farmhouse beers), saisons (Belgian farmhouse beers) and biere de garde (French farmhouse beers). Beers whose origins are in agriculture and whose releases coincide with the celebration of the hard work that the field laborers have put in.
The popularity and commercialization of the German festival that is called Oktoberfest, has helped to blend these celebrations into one. While its own purposes have been long-since been abandoned, it is today a celebration of Germanic heritage and culture.
Prince Ludwig of Bavaria and Princess Therese of Saxe-Hildburghausen. The first weekend, October 12, 1810 was the wedding; the second weekend, October 17, 1810, was a horse race. Each subsequent year was an anniversary celebration; though in 1812 the celebration was cancelled due to the Napoleanic Wars. In 1819, the city of Munich assumed control of the festival and has held the festival every single year since. The Oktoberfest Parade began in 1835 to commemorate the wedding; the parade marchers all wear traditional costumes and clothing. This year, 2008, is the 175th Oktoberfest Celebration.
Interestingly, there doesn't seem to be any real political significance for the marriage - the celebration was held simply because Prince Ludwig was a partyin' kind of guy. Over the years, this celebration has become more about Germanic History and Culture through the lens of Bavaria. This tradition includes beer, which was a staple of the Bavarian diet. Many of the finest and oldest breweries in the world are in Bavaria and the costumes of Oktoberfest, lederhosen and dirndl, are tied to the servant history of the region.
In America, particularly in the Bavarian-like region of the Midwest, we use the Oktoberfest moniker to celebrate both the Germanic heritage that many of us share, and the harvests that our farmers reap for us. Of course, it often seems that we just use it as an excuse to drink; but, frankly, I like to think that we never really need an excuse to drink - we can drink for any reason at all - and instead we use these celebrations to take a day to reflect on our heritage and those that have provided much of the raw materials that comprise the food and drink that we consume.