Ain't the internet a wonderful thing - people post complete crap and then dicuss it...
The BRCA and EFRA rule is that the dimension for length is 43mm +0/-1.5mm. That hasn't changed for years. What did change was that, as Danny says, when you use them they deform. So, BRCA and EFRA amended their Rule to say that the cell must not exceed 44mm in length at any time. Without this, drivers could have their race time disallowed, through not fault of their own, by having a used cell in their pack that was over 43mm.
IFMAR's Rule is 44mm max - no tolerance; end of...
Some cell manufacturers have taken advantage of this, produced cells over 43mm in length, and cited the '44mm' Rule when challenged. EFRA and BRCA decided last year to remove the 44mm Rule, and advised the manufacturers that from the release of the new homologations lists (31 Dec 07 submission dealine for BRCA) effective 1 April 2008, no cell over 43mm would be allowed for racing - the 44mm Rule, put in by BRCA/EFRA to help its drivers, will be deleted. The manufacturers have had 14 months notice. (I also believe that the International Standard for a sub-C cell is 43mm max, and that was what the original Rule was based from).
The original dimensions have remained unchanged for may years; there is no change of dimension that the manufacturer's aren't aware of, and when this is adopted it will be up to manufacturer's whether they continue to make '44mm' cells for non-European markets. If they do, cells from the USA (for example) won't be allowed in Europe.
As the photo shows, it is my understanding that the new Orion cell is 42mm nominal. Orion were told at the same time as every other manufacturer what the new Rule would be (14 months ago) and they have done something about it. IB have no one but themselves to look at, since it is their faulty cells that kicked off this debate (as Danny points out) and in an effort to reduce the risk to everyone, BRCA and EFRA have reverted to the original Rule.
All the other sub-C cells we don't use any more are below 43 mm (some 42mm nominal) so there is no change to dimensions. We don't use them because they don't give the performance of IBs, but they are as robust as cells always were. IB have pushed the envelope, and it is a generally held view that they have pushed it too far, and lost control of the quality in the process. I expect my National Association to give me the best guidance, and to do what's best for RC - BRCA/EFRA are doing just that.
As for capacity, I know of no class where capacity is an issue to the average driver any more, including 12th. To say we're all going to hell in a handcart because the capacity is going down isn't responsible. HTH