Ever since the dawn of mankind, as defined as since the release of FarmVille, Zynga has had the number one app on Facebook in terms of daily average users (DAU’s) until now.

Today, OMGPOP’s Draw Something is officially the most popular app on Facebook with 10.8 million DAU’s, compared to Words with Friends with 8.6 million DAU’s according to AppData.

Zynga still dominates the Facebook charts, Zynga is not number one on Facebook should give hope to other developers that you can succeed on Facebook without spending tons of marketing dollars and actually compete with Zynga based on creating a fun, viral game.

As Kim-Mai Cutler of Techcrunch points out, however, the fact that the number one and two game apps on Facebook are actually mobile games that use Facebook Connect to sign in (hence counting as a DAU) does not bode well for Facebook and its gaming business.

Facebook does not collect a transaction fee on iPhone and Android devices. In the case of the iPhone, Apple does.

The sad part of this story is that everywhere this news is reported or discussed, someone in the comments makes a joke that Zynga is probably working on Drawing with Friends to copy Draw Something as we speak.

The thing is, this joke is probably close to the truth.

Based on Zynga’s pattern, they probably are offering to buy OMGPOP as we speak. If OMGPOP says no, Zynga will work on a similar game and it’ll probably be called Drawing with Friends.

Draw Something is a social version of Pictionary (just like Words with Friends is social Scrabble, there I said it). So when Zynga does create their own very similar version they will rightly claim that they are improving on an existing game mechanic.

Still, with all of Zynga’s talent, aspirations, and money, it’d be nice to see them ahead of the curve.

As for OMGPOP and Draw Something, they are the current king of the Facebook hill so they should enjoy the view while they can. Drawing with Friends is probably in development and given how volatile the games market is on Facebook and mobile devices, it’s only a matter of time before another big hit game pops up the DAU charts. Hopefully, for Facebook’s sake, this next number one game on Facebook in terms of DAU’s will actually be played on Facebook and not a mobile device.