The US Millenium Challenge Corporation (MCC) and the British Deptarment for International Development (DFID) have signed a memorandum of understanding (MOU) to increase their cooperation in Africa. The MOU specifically pertains to Ghana, Malawi, Mozambique, and Tanzania. I didn't check, but I’m willing to bet those are the only African countries where both the MCC and DFID work.
The press release is short on specifics, but does mentioned a few areas of cooperation: data and statistics sharing and coordinated approaches to issues such as environmental protection, infrastructure projects, transparency in large-scale procurements, rigorous evaluation of aid effectiveness, future staff exchanges.
MOU's can be very useful, or a waste of paper. A lot depends on the wording, whether coordination is compelled or merely allowed by the document. Even more depends on how much the parties are willing to work to make the cooperation happen, particularly in the field. But a good sign all in all.