This month's ImagineFX magazine features some great illustrators (Todd Lockwood, Alex Ross, etc) taking on Blizzard art. The issue includes a 2 page spread of DEATHWING, a large painting (48" x 36") by Michael Whelan that Blizzard commissioned to hang in their corporate office.
Whelan recently wrote a "making of" feature on his website that details his process from initial sketches through composition and color studies to the finished painting. Check it out at: http://www.michaelwhelan.com/deathwing/