I’m currently evaluating the ‘community projects’ programme of the Guardian News & Media group (i.e., the series of ~12 partnerships which GNM has with voluntary organisations near its London HQ). In this article in the Guardian, I explain what we’re doing & why, why understanding impact is so difficult, and what I learnt about understanding impact from Albert Einstein and Ben Goldacre:
Measuring the effectiveness of the Guardian’s community projects
What else can giving learn from physics and medicine? A lot —>
Caroline Fiennes @carolinefiennes 
Corporate philanthropy is a very effect way of giving – when there is a group of individuals intending to provide aid to one charity. In our experience at Must Have Gifts – we provide charity gifts for groups, which work well for groups such as churches, business & youth groups. The gifts that groups are able to provide have a lasting impact on the communities they reach. For example we provide the Must Have Gift of A Roof For A Clinic – a gift such as this will save many lives and prevent many other illnesses spreading across communites – a great goal for any group raising funds – and extremely rewarding. You can find out more about us here: http://www.musthavegifts.org/how-it-works
Thanks Adrian. What you describe sounds like a mechanism for groups of individuals giving together – and they could be any individuals, not nec. brought together by sharing an employer. So in your example, the company is like the convener, rather than being a donor itself (which is what is normally meant by ‘corporate giving’).