Canada's toughest drinking and driving laws are now in effect in British Columbia. The new laws provide very stringent and immediate "administrative" penalties when a police officer determines that a driver has a blood alcohol level over .08, and lesser but still significant penalties if the blood alcohol level is between .05 and .08 (see this Vancouver Sun story and this CBC story for details). The new laws give police officers a great deal of power and discretion.
A colleague of mine who practices criminal law says that he is advising everyone he knows not to drive after drinking anything at all due to the new rules and to his belief that roadside screening devices and procedures are prone to error. If that is the broad consequence of the new laws, there may be some significant effect on winery tasting rooms ... the least of which may be to make sure that you increase your number of spit buckets.
Update: It appears that the above predictions have come true, at least to some extent. BC restaurants are reporting drops in liquor sales of between 10-40%. One winery owner reported that his on-site restaurant had seen initial drops in wine sales of 50%. There appears to be a great deal of confusion as to the actual effect of the new laws as well as if there is any permissible "safe" amount. For more information, please see this government page on impaired driving. This PDF chart of the new penalties may also be helpful.