I wonder the same thing. I was considering developing an app for the finappstore but I just don't have time at the moment. Currently all apps plugging into Yodlee must be built on the Adobe flex platform.

One interesting thing is that the developer forums on Yodlee site like pretty desolate. Here is part of a message posted on 8-26-2010 which has zero responses.

"There are almost 200 of you that have gone through the full developer registration process and have access to building and testing applications inside of Yodlee.

There are five applications that have gone through full certification and are available in the Yodlee FinApp store in BETA with another six applications in the process of certification right now.

The forum has been quiet with questions recently, so what are people working on? What's blocking you from moving forward?"

I wonder if people just don't know about this or if the flex platform is deterring developers. It seems pretty cool.