Just a random thought off the top of my mind:
What if one would create a campaign somewhere in a "Clickable Sandbox" and then copy that campaign over to Google, Yahoo, MSN, etc..? I have not read the Google API terms of use, but perhaps this is a way of circumventing the terms while still providing the ability to copy campaigns across networks?
Obviously this would not work for existing Google campaigns (as the "masters" are "stored" in Google), but for new Campaigns, the "Master" could always be "stored" on Clickable's servers and then "Copied" to Google whenever changes are being made. When copying the campaign over to Yahoo, you are not actually copying from Google => Yahoo, but actually from Clickable => Google, and Clickable => Yahoo.
(Once again, I have not read the Google API Terms of use, and so don't know if these "grey areas" even exist. But I assume the Google API terms have nothing against the ability to import campaigns from other networks?).
Best,
Alex