There are multiple ski resorts in the Banff area, including Mount Norquay, Sunshine Village, and Lake Louise. These are all within a short drive (20 minutes to 1 hour) from the town of Banff.
The snowfall in the mountains has been well above average this year, so that the snow conditions for spring skiing should be very good, even in early May. The Sunshine Village ski resort is typically open until the Victoria Day long weekend in Canada (May 21 this year).
Many Banff hotels offer shuttle bus to and from the ski resorts. Check with the information desk at your hotel for information on ski resorts, equipment rentals, ticket pricing, and bus schedules. Brochures are usually availabe in the entrance lobby of each hotel.
While there are no formal plans for a WWW2007 skiing expedition, attendees are welcome to pursue this opportunity if they so desire.
Graduate student Mingwei Gong at the University of Calgary has volunteered to be a point of contact for skiing-related questions. He can help you link up with others who might also be interested in skiing either before or after the conference (or even during!). Feel free to get in touch with him.