In Sweden there has been a huge increase in sales of RVs and though many do not use them all-year I personally know of three RVs used 9 months a year. There is also a very large number of especially German registered RVs going through Sweden every year, I do not know if they are used all year or not.
All over Europe they are more popular than ever, 20% of the Swedish sales are at the exhibition for RVs and trailers at Elmia, Jönköping. Never been but I'm sure it's huge and well visited and probably a lot of community information going on there.
Incidentally this is the same place they have Dreamhack every year, the biggest community gathering of geeks, gamers and e-sport lovers in the world.
My answer would have to be Yes, there is a strong community of RVers in Europe, but the RVs are smaller and far less year-round users than in the US. But keep in mind that Europe is a very diverse place, lots of cultures with different ideas. I've seen lots in west and central Europe, not as many in east and south.
As for links I can find you some Swedish links, would that be helpful?
Having spent 5 months the past spring in Thailand and visiting Malaysia and Singapore I can say I never saw a single RV. For the areas I visited, I can't see myself ever risking my or others lives by going in to traffic with one. The roads are of very varied quality (usually on the not so good side) and the general rules of the traffic do not make it easy for RVs.
Example: In Thailand they drive on the left side and any major road has a huge ditch or divider in the middle. If you want to turn right you have to find a gap in the divider and do a U-turn over 2-3 lanes with vehicles ranging in speed from biking to 130 km/h. Drive back then turn left in to the road you wanted to access.
I just want to clarify again after reading the comments posted on the question. As I've said I believe there is a strong community of RVers in Europe, while it is strong it is slimmer on the full-timers than the American is. I don't have any numbers on this, it is just the feeling I get from living in Sweden and enjoying traveling in Europe.
I also noted that a lot of hits I got were about accessories sold for RVs, campers, trailers, boats and so on. Such as solar panels. I feel a link to shops are not necessary to put in this list. I just noted a lot of it, and many pages mentioning this.
That said, here are a few links to Swedish sites that I found upon googling.
The Elmia exhibition official site for the caravan and camper show might be interesting. A lot of information on the Swedish version, not so much on the English. But they can probably direct you to organizations in the field.
husbilsklubben.se is perhaps the largest community in Sweden. Translates to "The RV Club". The link is to a discussion about taking the step of selling the home and moving in to the RV. It goes on to mention that most of them live abroad half the year, because to be honest everyone would be miserable spending a winter in an RV in Sweden ;)
My reasoning for calling it a strong community is because in this very chat several couples are throwing out contact information and inviting others to come visit to check it out or tag along for a trip and similar. They also mention having met couples from other countries having done the very same.
The newspaper Hallandsposten posted a picture article about a couple moving in to their RV.
byggahus.se (build house) has a miscellaneous section where there is a discussion about cost and living year round in trailer/RV. One post mentions 20 families with children living permanently in campers/trailers/RVs (doesn't specify, I suspect it is trailers) somewhere around the Swedish town of Ystad. Given that Ystad barely freezes over in the winter I would say that isn't a half bad place to do it.
"RVs - The hottest summer item right now" according to the paper Dala-Demokraten. (2011)
If I spoke German I am positive I would find the same over there, probably a lot more. Surely half the RVs I saw last year in Sweden were German registered. And with that many making it up here I am sure there are lots more going around Europe. I am sure they got lots of great communities.
Watching the British tv show Top Gear has lead me to believe there are many "...pestering motor-homes ruining the drive for the average Joe sports car driver..." ;) (Disclaimer: Not actual quote, just remember them bashing the motor homes and caravans)