This issue is a variant of The Amazing Spider-Man (Marvel, 1999 series) #526 [Newsstand Edition]. There exist further variants.
All 12 issues of "The Other" storyline running through the Spider-Man books have a variant cover by Wieringo and Kesel depicting Spidey swinging through Doc Ock's arms and exploding pumpkin bombs wearing a different costume in each cover.
Recap of the events which led to the start of this issue with credits and indicia.
"The Other: Evolve Or Die" Part 6 of 12. Story continued from MARVEL KNIGHTS SPIDER-MAN #20 (Marvel, 2004 series). Story continues in FRIENDLY NEIGHBORHOOD SPIDER-MAN #3 (Marvel, 2005 series).