The web forum is a front end to the newsgroup server for those who do not want to use a newsreader or who cannot access it because of a firewall.
The forum, as well as the NNTP server is based on VibeNews.
For Russian speakers, there is also a vibe.d section on the dlang.ru forums.
The following newsgroup server has a vibe.d group for general discussion. For now, almost anything vibe.d related fits there, ranging from suggestions, help requests or related projects. The NNTP server is located at forum.rejectedsoftware.com:119.
#vibe.d channel on freenode.net.
The public wiki is located on the github project page. It's content is still very limited, but anyone can quickly contribute interesting links or knowledge there.
Github issue tracker
The github project page contains an issue tracker. This is the right place to post any issues that come up and also for feature or enhancement requests. However, anything that seems like it might cause a longer discussion should better go to the newsgroup/web forum, which works much better for discussions.