Edit: It seems to be a feature of editing software that does things when trails get split.
1. What happened to my trails?
I find that some of the trails that I added a year or so ago no longer have my name on them. At this time OSM is having a debate over the 'gpl like' license and requiring people who use OSM data to attribute the database, yet the trails that I added now seem to have someone else's name on them and the contributions I made are not attributed as per the creative commons license.
An example is the central valley greenway
I added http://www.openstreetmap.org/browse/way/36058157/history back in June last year, but when I click on the Central Valley Greenway now, I see it's got a new number, http://www.openstreetmap.org/browse/way/41769632 and someone else is credited. I see the same thing at Mundy park, Delta Watershed, Burnaby mountain.
2. Where's my bridge?
Deleted, that's where. http://www.openstreetmap.org/browse/way/58568202/history
I went and re added it. It sucks that it went missing though.
It's a downer to see my local trail not have my contribution on it any more, and to have seen that bridge get deleted.
My advice to those of you using JOSM or other programs.. don't delete other people's contributions. Merge the data without destroying the attribution info.
Basically, don't take an eraser to someone else's trails and slap your name on it unless you're removing a completely inaccurate track (>30 meters accuracy) with a more accurate track (an average of several GPX traces for example)
OSM really needs work, and to fix it, you really need people to help, and that means accepting their edits, because the current status of the map in Vancouver is full of streets that aren't properly connected to other streets.
ie.. the people on Bear Creek Drive can't get out of their street! http://www.openstreetmap.org/?lat=49.1500425338745&lon=-122.831869125366&zoom=16
So be good to the guys who fix things like that. You really don't want to delete other people's fixes just because you imported some faulty data from Canvec.
You really want to have some new guy tell his friends 'Hey, I added THIS trail to your GPS' because that way, you'll get a lot of people making our local map better.