I know this is an old thread, but just to deposit some info:
Weed is decriminalized there; being a civilized place, they treat even hard drug problems as medical issues, not military ones. Weed was on the road to legalisation until the Conservatives won the recent national elections. A minority gov't, they should be in power around 18 months and they won't consider further action -- if anything they will try to tighten laws.
Coffeehouses/smoke shops that let you smoke it include at least one on Granville near Davie, 2-3 at the corner of Hastings & Abbot, and one on Commercial Drive. They are quite open & advertise what they do. But they don't sell weed, just equipment and drinks.
All public places are officially non-smoking in Vancouver . This is often ignored at the coffeehouses. They, as well as some bars, clubs, etc., have enclosed smoking rooms indoors for smoking. If it's not a coffeehouse, it depends on the place on whether they frown on smoking pot in there. My experience is that strip clubs are OK, regular bars not, but when in doubt, just ask a waiter/waitress.
I would advise you to follow the guide books and AVOID the drug market near Chinatown for buying it. If you are male, or an aggressive woman, you should have no trouble w/ any hassles by just walking around down there, but it is quite seedy; and I would not buy anything from anyone there. You are much more likely to get ripped off, IMHO, to varying degrees, & it's the place for harder drugs, it seems.
Some sites to check out for Vansterdam:
http://www.webehigh.com/city/detail.php?CITYID=2024
http://www.bcpassport.com/cool.html#smoke
http://www.marijuananews.com/