Just over a week ago I wrote that LivingSocial has become the top Facebook application. The company has continued to expand their lead and as of today have become the largest Facebook application ever based on monthly active users. Previously, Causes held the record of 26.95 million monthly active users. Today LivingSocial breached the previous record, jumping to 27.13 million monthly active users, up from approximately 20 million just over a week ago.

It’s an impressive feat yet what’s strange is the massive gap between LivingSocial and the second largest Facebook application: Super Wall. As far as I know, there has never been such a large gap between the top two applications on Facebook in terms of monthly active users. Causes, the previous record holder on Facebook, has tumbled from 26.95 to 17.182 million monthly active users. That’s more than a 36 percent decline since the redesign.

While LivingSocial is the largest application currently on the platform, the company as a whole is still behind Zynga and RockYou, who are the top two developers on the platform. Zynga jumped into the top position as of yesterday and they still continue to grow as of today. LivingSocial is rapidly gaining traction though as they are adding millions of monthly active users a day to their suite of applications.

Many companies that I’ve spoken to off the record claim that Facebook is going to be clamping down on news feed stories but not everybody has told me the same thing. It’s unclear what Facebook’s future policies will be though and as we’ve already witnessed, Facebook is willing to change the whole game overnight whether developers like it or not.

Unfortunately for Facebook this has made some of the larger application developers a bit sour as there is no guarantee that their market share won’t be erased practically overnight (just as we are seeing with “Causes”). While it’s fun to watch the application leaderboard change on a daily basis, also illustrates how fragile the platform ecosystem is.

LivingSocial may be the leading application and Zynga may be the leading developer for now, but could drastic platform changes down the road shake up the ecosystem once again?