From the band’s website, which includes a making-of video:
This Spring, we were on tour opening up for the B-52s, with shows all around the East Coast. One day while we were driving, Keith was browsing through the applications on the iPhone and came across FourTrack. We thought this app would be a great way to record song ideas while we are away from home. So we downloaded it, and I thought it would be a neat experiment to record the full band on a phone.
You could call me cynical for suspecting that part of the reason they did this was to get free publicity from Apple - which did happen - but I applaud The 88’s indie acumen.