EDIT: New file posted. October 21, 2009. BuildFullUrl function added.
This interface is for YetAnotherForum 1.9.4 Beta 2 and DotNetNuke 5.1.4.

Here is the complete source for interfacing YetAnotherForum 1.9.4 Beta 2 and DotNetNuke 5.1.4.

Copy the 4 files, DotNetNukeModule.ascx, DotNetNukeModule.cs, DotNetNukeModuleEdit.ascx and DotNetNukeModuleEdit.cs into your forum location (eg. DesktopModules/YAF/)
Copy yaf_dnn.dll from the bin folder to the root bin folder.

The source code for yaf_dnn.dll is in the coresponding folder.

Notes:
The Host must place the first forum on the portal. Admins may add forums after.
When a new forum is placed on a new page the new forum is created automatically.

Only the host can access the DotNetNukeModuleEdit functions.

Each time the forum is viewed, roles will by syncronized for the user viewing the forum.
This is one way only. DNN -> YAF.
If a role is deleted from DNN, it will not be removed from YAF. This must be done manually.
I suggest not to create any roles from within YAF.

I have posted some instructions of how to install here.