I've just looked on amazon and they say that amazon.com are releasing it on june 26 2007, But amazon.co.uk are realeasing a day earlier on the June 25 2007.
Popmart: Live from Mexico City was one of the first titles slated for release in the DVD format in 1997/98, and previews for it appeared on PolyGram DVDs of the time. But the PolyGram release was quietly canceled, leaving the DVD to languish until its scheduled re-release in June 2007, under the Island Records label. The DVD will be released in a one- and two-disc edition, similar to the DVD release of fellow U2 VHS to DVD release Zoo TV: Live from Sydney. Both editions will feature the concert in its original 4:3 aspect ratio, remixed with Dolby Digital 5.1, DTS 5.1, and PCM Stereo audio.[2] The two-disc format features the following bonus features on disc two:
* Bonus Tracks
o "Please," "Where the Streets Have No Name," "Discothèque" and "If You Wear That Velvet Dress" — taken live from Feyenoord Stadium, Rotterdam, July 18, 1997
o "Hold Me, Thrill Me, Kiss Me, Kill Me," "Mysterious Ways" and "One" — taken live from Commonwealth Stadium, Edmonton, June 14, 1997
* Bonus Music Videos
o "Staring at the Sun" (Miami Version)
Directed by Morleigh Steinberg
o "Last Night on Earth - First Night in Hell" (Remix Version)
Directed by John Bland
* Documentaries
o Lemon For Sale
o The Road To Sarajevo
o A Tour of the Tour
o Last Night on Earth - One Day in Kansas
* Popmart Tour Visuals Montage
Curated by Catherine Owens
* Extras
o DVD-ROM features
It was originally going to be on DVD in 1997! No updates as to September...yet.
Wikipedia is bullshit, it's completely inreliable. It was never supposed to be released on DVD in 1997.
It will be released before this summer ends, that's the only thing that's confirmed.
This one's really funny. 
) 
.