As a note, are you aware of the Google Linux search
? It's pretty good at only returning Linux-related articles (you may already be using this, but a lot of people don't seem to have come across it).
I wouldn't worry too much about the age of articles, since the underlying problem of VPN remains the same, and the networking technologies remain the same too. Nearly everything you'd need is part of core Linux, so will be exactly the same in any distribution (be it a recent one or one from a few years back). The Linux Documentation Project
is normally an excellent resource, and a Google Linux search for "vpn howto" turned up this rather good document
. As you'll see, it's based mainly around SSH and PPP, which haven't really changed for years.
What you may
find is that recent trends e.g. firewalls/NAT aren't covered as much as they could be (I don't know, I haven't read it through) - but even if that is the case, it'll still give you a good grasp of the requirements of the problem, and the broad steps to take to solve it. Chances are, if you read through it, you'll be able to set one up with perhaps a bit of Googling on specific areas.