Is it possible for a rack designed to store servers on their side (blade style) to be EIA-310-D-compliant? I suspect not, but reading the spec I couldn't find any explicit statement about it.
I know a design house who wanted to mount their Xserves from the ceiling, in a rack made by a boutique company (which has since gone out of business). I told them this would probably affect heat distribution adversely, but I wasn't able to find a definitive printed answer for them.
Edit: Background information - one of the considerations here is that if the servers aren't stored in a EIA-310-D compliant rack, it could void their hardware warranty.