Who are we talking about?
These two mugs.

Where is this taking place?
It's all happening at the Artesian on 13th, 2627 13th Avenue, Regina, SK. Here is a map for those who are more visually oriented:
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The Artesian is a former church that's been converted into a performance space. It's hip, it's happening, all the cool kids go there, and you should definitely visit their website for photos and more information about the venue.
When should you be there?
The ceremony will take place Saturday, September 1, 2012 at 7:00 p.m. There will be cocktails beforehand, beginning at 6:30 p.m., and appetizers, a dance, merrymaking, and general tomfoolery following. We'll run until 2:00 a.m. or until we run out of booze, whichever comes first (I'm betting that 2:00 a.m. thing).
What should you wear?
Tamara says you should dress "comfortably". My father is at his most comfortable in underwear and a Fleetwood Mac T-shirt, but let's consider pants to be the minimum standard and build from there. So if you're Barney Stinson, you'll probably wear a suit. If you're 1st century BCE Roman Emperor Julius Caesar, you might be more comfortable in a toga. I'm sure most of our friends would fall somewhere comfortably in the middle.