How common are international collaborations?

Common enough. Here is a short list of collaborations between American and Brazilian brewers:

Brooklyn/Wäls - Saison de Caipira
Stone/Bodebrown - Cacau IPA
Modern Times/Dogma - Modern Dogma
Sixpoint/Invicta - 6 o'clock
Green Flash/Seasons - Holy Cow

 

The only one I can remember off the top of my head was Stone/Jolly Pumpkin/Nøgne Ø.

http://www.beeradvocate.com/beer/profile/7730/54355/

 

Green Flash/ St. Feuillen (sp?)
Tons of Mikkeller/Amager/To Ol/De Struise/De Proef/Stillwater/Evil Twin/Etc
Schneider/Brooklyn
FFF/Mikkeller
The recent SN Okto
Gnomegang
Pipeworks/Great Leap

 

I Australia we have:
Mikkeller/ bridge road Dark harvest,
Temple and Weiheinstepahn : Ufikinator bock ( shite)
Nomad/Victgory Secunda Pils
Bridge road Nogne O India saison and Aurora borealis
Moon DOg Rogue: beard Down under Barleywine
Nogne O Holgate half a world away IRA
still water exit brewing, fingerlime saison


im sure there are others

 

I see a lot of American breweries collab with German for Oktoberfests.

 

The brewmaster collaboration series with belgian brewers and American ones aren't too tough to find.

 

Mikkeller does a lot.. So does De Proef.

 

Surly's 1349 and Todd the Axe Man were both collabs with Scandinavian brewers IIRC

 

We get a fair number

A large chain of pubs here flies brewers from around the world into the uk and gets them to brew at various breweries for their seasonal beer festivals. Usual suspects are the likes of Stone, Sixpoint, Societe, Nogne O, Yeastie Boys etc. They tend to brew at the older regional breweries and some of the beers tend to just taste like those breweries normal beers, like Caledonian, Everards and so on, but some are real winners, the Stone and Sixpoint beers made at Adnams have been excellent and the best that I've tried so far was John Kimmich brewing "Enraputred" at Adnams, it was an absolute corker ( Broadside base with hops from the alchemist's Rapture)

There's a few others besides that, like Hill Farmstead/Siren, Brooklyn/Williams Bros

 

http://www.sirencraftbrew.com/rainbow-2015-pairings/
The Rainbow Collaboration is now an annual event.

 

Dogfish Head and Birra del Borgo (Italy): My Antonia

Also while it is not strictly a collaboration but more of a corporate merger, brewing partnership, whatever you call it; I'm sure we'll see something between Lagunitas and Heineken after they join.

 

Other Half (NYC) / Garage (Spain)

 

Is the Ovila series a collaboration between Stone and a foreign monestary/abbey?

 

No, it's Sierra Nevada and the Abbey of New Clairvaux in Vina, California

 

Isn't pretty much everything released by a phantom brewery (i.e. Mikkeller, Evil Twin) technically an international collab since they don't have their own physical brewery/location?

 

I had a freigeist/jester king smoked sour collaboration recently.

 

Sierra Nevada Oktoberfest is a collaboration with Brauhaus Riegele in Augsberg, Germany. It is damned good and very fresh from Mills River, N.C.

 

Evil Twins collaborations are pretty nice if available in your area.