I looked at this earlier this year. Lack of API access means that we cannot build an application similar to Simple in the UK. I e-mailed several banks and most of them did not reply.
My understanding of Simple is that the services they provide are simply provided by their partner bank, http://www.thebancorp.com/, which is a regulated financial institute. I'm not sure how the issue of API access is relevant but this may be my lack of understanding more than anything.
That link will expire once the thread 404s and imgur does not accept files over 2MB so here is an alt link from tinypic: http://i47.tinypic.com/30vllw6.jpg