It's pretty much what they have been saying all along; Heroku switched to random routing to support other stacks than only Rails and they kept the routing infrastructure between Cedar and Bamboo the same, resulting in an undocumented performance degradation for large customers still on the old stack or running non-concurrent web frameworks on the new one. The last part was an oversight on Heroku's part, but the rest makes sense, especially considering Cedar supports other stacks than just Rails, including massively concurrent ones(Nodejs, Play, etc.).
The rest of the whole thing was people who were unsatisfied by the change and wanted the old product offering to return and/or felt shortchanged by Heroku. Luckily, Heroku doesn't lock you into their platform like GAE does, for example; it's essentially a bunch of shell scripts to deploy binaries on EC2 workers, a hosted instance of Postgres on EC2, some routing and ops as a service. Anyone who wasn't happy about the change could've contacted Heroku to say "you said we would be sold non-random routing, but you've sold us random routing" or moved their app away to another provider or even their own servers.
Does this suck if you wanted the old service? Sure. Witness the flak that the canning of Google Reader got and it's obvious that discontinuing old services isn't exactly a popular decision. On the other hand, you can self-host (it's massively cheaper than Heroku) or switch to another provider. And if there are no other providers that specialize in Rails hosting, isn't that a business opportunity?