Twice now in the past week I've been asked for market data on IHE XDS and related profile adoption, directly or derivatively from one querant ... ONC. I'm not a marketer, but I know some resources where you can scan for data on this. By the way, as far as IHE XDS goes, I'll bet there is more freely available information than on any other interoperability specification. I challenge you to find this kind of data available on any other interoperability specification without paying a pretty penny for it (Market Analysts take note, people want this data!).
I'll start with the Where in the World is XDS Map which is a crowd-sourced map of XDS implementations. I started that a couple of years ago in response to a query broadcast by a market analyst from Gartner. As Wes points out, people have a lot of incentive to get on the map, but not to update it. I do a refresh every now and then from a number of sources (the HIMSS Interoperability Showcase is a great place to learn about these implementations). But that was February, and this is July, and my notes from them are still sitting on my desk because other things have been more pressing.
Another good source is IHE Integration statements, which you can get to via the IHE Connectathon testing results site. Any system listed there shows what profiles a vendor has TESTED. If there is a folder next to the vendor, that provide a link to their integration statements, which can be inspected to determine what systems are shipping with a particular profile.
A third source is the IHE Integration Statement registry that has recently been rolled out. I know there are systems missing from that, for a variety of reasons, including the newness of that system.
A fourth source is the Open Source list that I keep track of. These don't often have published integration statements nor registration entries.
A large number of systems in the US are using CONNECT Open source, and they keep track of adopters on this page (which is another one of my data sources for map updates).
Lastly, although in part probably due to the XDS Map, which I originally created for a one person audience. Gartner published it's Hype Cycle for Healthcare Provider Technologies and Standards, 2010 last year (around this time). IHE moved from Sliding into the Trough to Climing the Slope. The author of that report (my audience) was asking some of the same kinds of questions about XDS adoption more than a year and a half ago as ONC is asking now.
So, if you want data about adoption of XDS, I've given you some great places to start. It's neither in my skills, nor my role1 to put the rest of it together for you, but at least you have a good starting point.
P.S. HIE industry, please take note. People are asking about your deployments. To add entries to the XDS map, just contact me for access.
1 I do work for a vendor with products in this space. Any market intelligence that I have that is NOT public knowledge isn't something that I can freely share with others -- sorry.