I see a v0.4.9-rc3 from 6 days ago out on docker hub:
https://hub.docker.com/r/particle/buildpack-particle-firmware/tags/
but no v0.4.9.
Coming soon?
0.4.9-rc.3 is 0.4.9 so you can continue to use that image. I just pushed a 0.4.9 tag which contains some small tweaks to the application code for library compatibility - system firmware is the same.