mpls = multiprotocol label switching, mostly to toss internet packets encapsulated to an some rfc3032 headers.
(somewhere i've read that some people think mpls stands for multipurpose problemsolving labor substitute:)

i'll evangelise new, and describe existing mpls related technologies here, so new content will be added as ietf progresses with it's work. be warned that these are just summaries of the given protocols from my point of view, you should take a look at the given rfcs/drafts. (drafts may change frequently so you should reread them at least when they become rfcs... not to mention the constants... just sayin')
here are the topics already available:

polynomial key architecture
network service header
bit indexed explicit replication
segment routing
traffic engineering
virtual private network
path computation element protocol
resource reservation protocol
label distribution protocol
border gateway protocol
open shortest path first
intermediate system to intermediate system
label switching
provider edge router
provider router
label switched path
mpls label header

in case you found an error on this site or would like to see an emerging technology here, feel free to contact me.