Ask HN: HIPAA Compliant Hosting Providers?

I have over a decade of experience in medical application development and support. Recently, I've been exploring the possibility of establishing my own company based on an idea and prototype product I've developed for the medical community over the years.

Long story short, finding HIPAA-compliant hosting at reasonable cost with all of the features expected of a "cloud" provider is proving to be difficult. It wasn't until recently that HIPAA amended it's rules related to hosting of PHI (protected health information) applications. Though it did not state it directly, they now require Business Associate Agreements to be signed by hosting providers and they (providers) must also abide by certain standards and rules related to vetting staff and training and such (which isn't new, but the agreement is).

This is nothing really new, but it opens up the possibility of using "cloud" providers now, as far as I can tell. Problem is, it appears Amazon won't explicitly state if they will sign the required BAA regarding their AWS platforms, which is a no-go as it could possibly be seen as an act of "Willful Negligence" on my part if that document is not signed by the hosting provider. They have "guidelines" on how to create HIPAA-compliant hosting setups with EC2 and S3 (http://d36cz9buwru1tt.cloudfront.net/AWS_HIPAA_Whitepaper_Final.pdf), but don't clearly state that they, themselves, are HIPAA compliant. Apparently they even have their own interpretation of the guidelines and betting on them being right is not a risk I'm willing to take at this point.

So, tl;dr. That being said, Rackspace and Microsoft (when paid enough money) will sign the BAA, but is their Public Cloud, in anyone's (non-legal, obviously) opinion HIPAA compliant then? Is there anyone out there with experience hosting HIPAA compliant applications using Amazon or another service?