Children's writer N L Sharp is organising a triple writing retreat in Nebraska in October '07, April '08, and October '08.
The programme is called "Novel Retreat in 3 Acts". The first "act" involves learning about character and plotting and brainstorming ideas for a first draft.
The second act involves revising the completed draft, gaining critiques of your draft, and reading the work of three other participants.
The third act involves submission and marketing and is run by an editor and an agent.
More information is available on N L Sharp's website