It is virtually impossible due to Sybil attacks. Bitcoin is as close to a decentralised timestamp system as you will get.
nope, can be done. I have a working model. see:
http://www.stanford.edu/class/cs240/readings/lamport.pdfif you review that paper maybe we can discuss how to do this, otherwise I'll save it for later.
later friends! -bm
Oh someone beat me to it.
Oh well, it's a popular paper I suppose.