putting "/tmp" to memory

[kellyremo]

"to memory" means: mounting a ~2 GByte filesystem [ tmpfs?, or ramfs? ], and put the "/tmp" on it. [ e.g.: 4 GByte ram in the pc ]. what to write in the "/etc/fstab"?
 
 I would like to collect the [ answers too:P ]:
 
 Advantages:
 - Memory is way faster then HDD/SSD, so it could speed things up
 - "SSD amortization" is less
 
 Disadvantages: 
 - Security? [ how to set this up to be secure? any clear howtos/links regarding it? :O ]
 
 Really thank you for any good help...