Given a paragraph, your job is to generate a question that can be answered from the passage. The answer to your question should be a single entity, person, time, etc. that can be extracted from the passage.

On 28 February 2008, Kibaki and Odinga signed an agreement on the formation of a coalition government in which Odinga would become Kenya's second Prime Minister. Under the deal, the president would appoint cabinet ministers from both PNU and ODM camps depending on each party's strength in Parliament. The agreement stipulated that the cabinet would include a vice-president and two deputy Prime Ministers. After debates, it was passed by Parliament, the coalition would hold until the end of the current Parliament or if either of the parties withdraws from the deal before then.
When did Kibaki and Odinga sing an agreement on the formation of government?