Prelude currently has several official & unofficial support channels.
For questions, suggestions and support refer to one of them. Please, don't use the support channels to report issues, as this makes them harder to track.
Most internal discussions about the development of Prelude happen on its gitter channel. You can often find Prelude's maintainers there and get some interesting news from the project's kitchen.
The official mailing list is hosted at Google Groups. It's a low-traffic list, so don't be too hesitant to subscribe.
If you're into IRC you can visit the #prelude channel on Freenode.
It's not actively
monitored by the Prelude maintainers themselves, but still you can get support
from other Prelude users there.
We're also encouraging users to ask Prelude-related questions on StackOverflow.
When doing so you should use the emacs-prelude tag.