How they do this?

I have seen some forums (mainly vBulletin) having integrated usenet groups in them as such that they are a part of the forums.
My question is that only vbulletin supports this?
Is this possible for other boards not using vB.

vBulletin doesn't support usenet groups. That is a hack, which can be found at www.vbulletin.org . You are allowed to add hacks to your board such as that one, but you do it at your own risk. The reason vB moved the hacks to vB.org was because they don't want to give support for hacks, which is perfectly understandable.

Surely, this could be implemented on other forums, and it may very well be available, but I haven't been following hacks for other forums.

Thanks for that info. :)
I will too try to find one for my upcoming board.