I've noticed that the container images for Traefik version 2 published to Docker Hub come out approximately every 2.5 weeks. Is there some document or GitHub issue query we can follow that would allow us to better understand how far away we are from each release?
Our goal is to track development more closely. When a change gets committed that we'd like to try, should we be building our own image? Is there a "nightly" (or similarly fresh) image published elsewhere that we can use?
Published releases get pushed when they are ready 
Unfortunately the release tracking is internal, so it's not something you can query.
You can always use the containous/traefik image, with the experimental tags, that are built off the head of each release branch:
containous/traefik:experimental-v2.0 will give you the most recent build on the 2.0 release.
Please be aware that this is a development image, and may be subject to change, and is not guaranteed to work, or be functional, as it is not a release image.