The National Science Foundation has just put out new solicitations for the Division of Environmental Biology's core programs and all programs in the Division of Integrative Organismal Systems. With the single exception of LTREB renewals, all core programs in both divisions now require the submission of pre-proposals. This includes regular research proposals previously submitted through the Grant Proposal Guide (GPG), and cluster program descriptions. Other solicitations (such as, but not limited to, plant genome research, ecology of infectious disease, coupled natural-human systems, and Assembling the Tree of Life) do not require preliminary proposals. This requirement does not (yet) apply to other divisions within the Directorate for Biological Sciences.
In both cases, preliminary proposals to these programs will be due in January each year, with invited full proposals due in August. Both divisions will also limit investigators serving as PI, co-PI, or lead senior investigator of a subaward to participating on no more than two preliminary proposals per year per division solicitation.
According to the NSF FAQ released along with the solicitations, the divisions expect the success rate of preliminary proposals to be "quite low." They are hoping, however, that the success rate for invited full proposals will be on the order of 25%-35%, which is an improvement over the current rates.
The combined DEB/IOS FAQ, the new DEB solicitation, and the new IOS solicitation can be found on the NSF web page.