PRAMFS, the Persistent & Protected RAM File-System, is namely intended for embedded systems where there is often a chunk of non-volatile RAM (NVRAM) separate from normal system RAM. PRAMFS is intended to be a Linux file-system for these non-volatile RAM blocks. Unlike tmpfs and ramfs, data in this file-system spans reboots.
For those interested in more technical details surrounding this RAM file-system, visit pramfs.sourceforge.net. The latest patches for the Linux kernel can be found at LKML.org.
At this time it isn't clear whether PRAMFS will make it into the Linux kernel. "Even if the code won't be in mainline the review is really useful to me, so any comment is welcome." While it is the weekend, at the moment no one has commented on this set of 17 patches.