The original Smithsonian Collection of Classic Jazz is a cornerstone of many jazz record collections. Long out of print, it's also hard to find, and if you do find it, you'll pay a premium.
Good news: Jazz: The Smithsonian Anthology (no longer "classic") will be released on March 29. It's 80 percent new, with 111 tracks (vs. the old 95) on 6 CDs (vs. 5) covering the years 1917–2003.
Why stop at 2003? I guess that's a question to ask the 43-person advisory panel or one of the 35 contributing writers or 145 total contributors. (The original seems like it might have been a simpler endeavor: selected and annotated by Martin Williams, with biographies by Ira Gitler.)
John Hasse, a fellow Carleton graduate (and author of the definitive Ellington biography Beyond Category: The Life and Genius of Duke Ellington), was on the selection committee and served as one of the producers.
The set comes with a 200-page book. A complete track listing is available here. SRP is $107.98; you can preorder and save $18 (at the moment; the preorder price supposedly goes up soon). Amazon has a preorder price of $96.95 and free shipping.