He uses Ashdown heads with WEM cabs. He plays a Fender Jazz, but I think on the album he mainly played his EUB, and his pair of Status 4 and 5-strings (fretless and fretted). That's what I saw on the AOL Sessions where they played a couple of songs from the album.
Here's the wikipedia quote: 'During David Gilmour's On An Island tour he is usually seen sporting a 3-tone sunburst 1961 Fender Precision, a vintage Fender Jazz, a Status Vintage GP, and an EUB (Electric Upright Bass)'
'Amp wise, nowadays he is mostly seen with Ashdown ABM heads and WEM cabs (equipped with Blue-cone Ashdown speakers, as Watkins Electric Music cabs are no longer being made).'