Supply of, and demand for computational capacity is elastic. Some companies are are falling short, others have capacity in abundance. More often than not the need or surplus in computational power or storage capacity is temporary. Wouldn't it be wonderful if the surplus of one corporation could (temporarily) alleviate the wantage of the other. A consortium of ten organisations from six European countries started on a collaborative project to enable just that. The Contrail project aims to design, implement, evaluate and promote an open source computational cloud wherein users can limitlessy share resources.