Thanks for the heads up, I've reached out to someone at Google that should have access here. I haven't seen any notification that Google was killing this service (unlike the link shortener they had all previous GWT versions use), so this comes as a surprise to me too. Hopefully this is an oversight they can correct.
I have most other of the now-lost releases archived, but now that one in particular - is there any chance your or one of your team members have a downloaded copy of 2.7.0 (which we can confirm from its hash at
https://www.gwtproject.org/versions.html) that we can reupload elsewhere?
Versions that were hosted on Google Storage:
2.9.0
2.8.2
2.8.1 - no backup
2.8.0
2.7.0 - no backup
2.6.1
Once we have a copy of 2.7.0 and 2.8.1 we'll have all the currently missing versions and I'll work on getting these rehosted and relinked