DDG founder here. We started out solely with our own crawler, which we still use for various things, e.g. finding and removing 50 million+ parked/spam domains. But we do use Yahoo BOSS as well.

However, we do not use BOSS straight up. We re-rank, omit, edit, merge, etc. in ways (I think and hope) yield much more relevant results, especially for more specific queries.

The Yahoo/MS search deal shouldn't effect us. We already have Bing in place as a backup and could easily switch to Ask's feed as well. We treat them as somewhat of a commodity, i.e. an output of the Web link graph, with our ranking stuff on top doing the important "last mile" work.

Thx for your feedback about news & images.