It is on DVD in the US but only at Borders book store now and will get a wide release March 4th

"The miniseries based on Terry Pratchett's 20th Discworld novel comes to general release on March 4th! The 2-part, 189-minute production on a single DVD is already available exclusively at Borders but will "go wide" via Genius Entertainment on the first Tuesday in March, becoming available through other retailers. Cost is expected to remain at $19.99 SRP, and nothing on the disc is expected to change."