yes, the song is over one hour long (63min 31sec). it's heavy as hahahaha and awesome.
I will completely concur with the author of the review of "Jerusalem," who said that this song (heard here as Dopesmoker, in all its 63 minute glory) is certainly a love-it-or-hate-it affair. Most people would hear this and immediately dismiss it as noise. Others would find the intricate sounds buried throughout, and appreciate this piece for its sheer genius.
Most metalheads know the story of Sleep, the band who only made two albums and this song, all of it containing less riffs than one of your typical thrash songs. They were contracted to a big record deal, and recorded this song. Needless to say, the record company didn't approve of what Sleep had layed down: a little more than an hour's worth of stoned jamming. The contract fell through, and Sleep disbanded. Years later, the song was released in a 52 minute incarnation known as "Jerusalem." Now, we finally get to hear and experience the entire song, along with an unreleased track.