Pretty much as what the title asks. Any ideas anyone? Is there any particular, technical limitation for using this technology with CF cards?
Here is the latest answer on CF adapters for the 5DmkII and the 7D, on our site.
Ziv. Eye-Fi co-founder
Thus far, Eye-Fi does not support compact flash. They have a page on their website that lists known issues when using an adapter. These issues include a reduced wireless range of the Eye-Fi card as well as a potential for file corruption.
I'm not aware of any competitor's products which offer similar functionality in a CF card. I do note however that it seems DSLR manufacturers are starting to move to SD from CF, with newer models from both Canon and Nikon favoring the SD cards.
There seems to be some evolution on that point. Eye-Fi seems to be willing to offer CF support, by certifying CF adapters for their SD Eye-fi, starting March 2015. More infos on their website:
You will find a how-to guide and a list of compatible cameras. And also some words on possible drawbacks, like slower transfer times.
I strongly doubt there's a technical reason. I'm sure that they just don't see offering a CF version as profitable.