I haven't seen mention of it yet, but I came across it today and thought it worth posting.
There have been waypoints added to a few places, e.g. Plains of Ashford. I had 100% previously on one of my alts only to find him at 98% now, missing a waypoint. This wasn't on any of the maps on the wiki that I could find, but after poking around I did discover it was way down south in a previously uninteresting area. It seems these new waypoints are connected to the new guild missions, and as such it's pretty tough for a level-appropriate character to get there safely by themself.
Also, while tripping the new waypoint did take me back to 100% from 98% I did NOT get a second map completion reward. Just FYI. It does seem to count towards 100% world map completion, however.
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GW2 Wiki's patch notes added footnotes regarding the two new waypoints.
They DO count towards zone completion, and towards ultimate map completion - BUT! - someone who already has 100% map will NOT have that status revoked. They have their title, their achievement, their rewards, and the associated rewards for the zone completions.
So, you don't get anything for re-completing, other than the XP for discovering a new waypoint, and for having the zone say "100%" again.
(That reminds me... I still need to grab the one over in Brisban.)
"As the good archmage often admonishes me, I ought not to let my mind wander, as it's too small to go off by itself." -Danilo Thann