As Github.com lacks afaik a binary hosting / download feature and Google Code closed its service (no new projects) - it would be great if all the Sourceforge mirrors (heanet, etc.) would be coordinated from an open source community instead of coordinated by Sourceforge.org. There is definitely a need for a binary hosting and mailing list website for open source projects, to fill the hole that Sourceforge may leave behind.
I remember the "BerliOS" from a Germany's Fraunhofer institute that was a kind of clone of Sourceforge, a open source project hosting service. It was closed in 2013 and some valuable code and binaries are lost forever.
Github does have a pretty good binary hosting / download feature, it's called Releases. There's even an API to automate it. It's not very widely used, perhaps because it only rolled out it 2013.
As for mailing lists, I guess their excuse is that they already provide possibilities for discussion in the issue tracker (which can be also interacted with entirely by mail). This is appropriate as a forum for developers - but not a forum for users, which would be out of Github's scope, IMO.
I agree that this would be the best recourse if we could manage to muster some sort of coordinated exodus of mirrors. Mirror providers have at least some sort of power over SF due the service they are providing, something that project authors do not have. Many of the mirrors I think are academic and I don't think they too happy about SF being such leech that they are.
These are two popular mirrors in the UK & Ireland (both academic institutions):
http://www.mirrorservice.org/ (University of Kent)
http://ftp.heanet.ie/ (Ireland’s National Education and Research Network)