This should be interesting. NSF's Division of Molecular and Cellular Biosciences is moving from submission dates for investigator-initiated research projects* every six months to every eight months. And limiting the number of proposals as a PI or Co-PI to one per cycle. Read the details here. And here's the new Program Solicitation.
Apparently these changes are a trial and only apply to MCB. So far. The rationales are that a) the eight month cycle will give PI's whose proposals have been rejected more time to adequately respond, and b) the limit of one proposal as a PI or Co-PI (note the or) will reduce the load on reviewers.
I'm sure this will cause much wailing and gnashing of teeth. Personally, I think this will be good. The NSF typically takes six months - sometimes more, sometimes less - to get panel summaries and reviews back to PI's. With the six month cycle that means those PI's have little to no time to turn around and revise their proposals. Many simply can't and end up waiting until the next cycle, twelve months after initial submission, to send in their revised proposals. The eight month cycle should help alleviate this. Planing for submission of renewals, particularly over the next year or so, could get a little tricky - I know I'll have to think carefully about my own renewal - but every major change will have it's shaky transition period.
On the other hand, the longer cycle time (but shorter resubmission time) could lead to larger panel and reviewer loads. Limiting PI's to a single submission should help there. Although, in my experience as a MCB reviewer and panelist (and of course YMMV) it's uncommon for PI's to have more than one proposal submitted simultaneously. I'm not so sure about the "PI or Co-PI" clause though. I would have preferred that it be limited to just one as a PI, or perhaps one as PI and one as Co-PI.
Want more info? The NSF has prepared a FAQ. My favorite question and (non-)answer:
21. Question: What should I do if I was planning to apply in July but now I can't apply until September?
Answer: PIs have two additional months to develop their proposals further. The additional time should allow PIs to prepare fully compliant and competitive proposals.
Wail and gnash to your heart's content in the comments.
* These are the typical (and majority of) proposals that are submitted. i.e. Not those submitted in response to a specific program.