Another +1 for SkyDrive - especially given the new release of the desktop syncing update (which was the reason I've just searched for this thread).
I've been a big fan of Eye-Fi since I saw the early concept designs were blogged about. I've had one now for a year or two but don't use it enough because the software is a little clunky and doesn't really fit with what I want to do a lot of the time. If it could automatically upload to a folder on SkyDrive that would just be awesome for me as this folder would then sync to my Windows phone, multiple PCs (home, work etc), my iPad, etc.
I also read previous posts regarding issues with the API, however I believe these are all more open now. Overview of the API is here - (as a new user, I couldn't include a link, Google for "SkyDrive APIs for Docs and Photos—now ready to cloud enable apps on Windows 8, Windows Phone and more") - and it appears that when that was written (Dec 2011) they added full support for SkyDrive and Photos (I've not read in detail, but perhaps your developers could take a look?). Furthermore, Windows 8 will be heavily integrated into these cloud services, so it may be worth getting on board in advance of that all kicking off.
Really hope to see some progress if possible