I want to announce that the private message system on the main site is being phased out.
From now on, all private messages should be made on the community forum, not on the main site.
You'll notice that the link in the header on the main site now directs you to your messages on the community forum. You can still access the private messages from the main site through your profile page, but these messages are now in a read-only state. If you want to write new private messages, you have to do it on the community forum.
Soon, access to the old private message system will be removed completely. I'll announce more details about as they become available.
The reason for all this is that the replatforming of the main site is made far easier if I can export as much functionality as possible to the forum. I would like for the main site to be an application whose only job is to make it a joy to find the tabs you want. All functionality related to community interaction I'd like to have take place on the community forum.