Given that Yahoo! is moving to be much more about the content it makes sense that they are doing this kind of research into what makes stuff shareable.
No surprises is that great content works and that’s where you should put your effort behind. Middling content needs to have its game upped and people will share things a whole lot easier if you optimise it for them. Interesting that publishing frequency doesn’t have much of an impact, despite what publishers have believed. The first 24 hours are critical in terms of sharing. As a rough rule of thumb one Facebook like is equal to 100 page views.
How, why, best and future are power words for shareable content. More information here – Yury Lifshits. Ediscope: Social Analytics for Online News. Yahoo! Labs, Tech. Report No. YL-2010-008 (PDF document).