Memory file systems

[Chris Ross <cross+netbsd%distal.com@localhost>]

  Quite some time ago, I remember there being a conversation about  
the pro's and con's of mfs vs. tmpfs.  There may, for all I've  
tracked, be further "fast non-durable file system" options now-a-days.

  My basic question is, why are there both mfs and tmpfs, what are  
the pro's and con's of each, and which (if either) is likely to  
receive more support/attention in the future?

  Thanks, and I hope I didn't poke into a political/religious issue...

                             - Chris