[robski]

It does appear you can get digital versions of the optical slave triggers. (peanut) A tad more expensive.

"WEIN products has duplicated the entire line of its popular solid state batteryless slaves in a digital format that can perfectly synchronize with digital preflash cameras."

The Wein PN-XLD for example.

This talks about coping with a 2 preflash system used on Nikon. From what I recall from my past reseach is that Canon has 1 preflash. So I don't know if they will cope with both or only Nikon. Info on this product is a one liner and a bit vague.