It might help interested parties to know:
Is Ollie neutered?
Is he cat/small furry friendly?
Can he live with other dogs? Other males?
Any health history is also helpful.
Can Ollie stay with your friend until a home is found, rather than going into kennels? Many shelters are full to the brim, but if he could stay where he is some might be able to help in placing Ollie even if they did not have space at the moment.
You might have your friend get in touch with Labrador In Not - this is a German lab/retriever rescue site, but it can't help to spread the word. Because breed rescues are not so common here Swiss dogs in need are also often posted in the relevant German sites. And Swiss folks looking for a specific breed often turn to the German rescue sites. And of course, someone across the border looking for a lab may be interested in adopting this dog.
http://www.retriever-in-not.de/
In the Zürich area, Tierheime Surber and Pfotli have excellent reputations - they would be good people to talk to.
http://www.tierheim-surber.ch/ http://www.tierrettung.ch/
Your friend should also list Ollie on the Tierschutz databank. Individuals can also post here - the database is not restricted to rescues.
http://tierschutz.ch
Another place to list Ollie's details is the Mein Hund discussion forum:
http://www.mein-hund.ch
She could also try talking to the various Hundeschule in the area - often trainers know of someone looking for a dog, or can at least pass the word along.
And, of course, posting notices (pic and description) in area vet offices is helpful - most vets have bulletin boards in their waiting rooms.
This is a long shot - but if Ollie is pedigreed, your friend might also call the Retriever Club of Switzerland, the SKG breed club. They are not (generally) into rescue, however as these are all lab people a member may informally know of someone looking to adopt a lab. Some breed clubs keep a 'Notfall' list - don't know if the retriever club does, though.
http://www.retriever.ch
Another place to list Ollie (another lab rescue forum -don't know anything about these folk, just found them googling...)
http://www.retriever-hilfe.de
I'll start asking around as well - I'm mostly involved with collie rescue and collie people, but one never knows....
edited to correct link--