For those that didn't notice,
http://www.audiovideohd.fr measures black levels in their reviews:
JVC DLA X7, THX mode, high lamp, iris open: 0.09 lux
JVC DLA X7, user mode 2, calibrated, low lamp, iris closed: 0.02 lux
JVC DLA X30, calibrated, high lamp: 0.04 lux
JVC DLA X30, calibrated, low lamp: 0.01 lux
JVC DLA X70R, calibrated, high lamp, iris open: 0.01 lux
JVC DLA X70R, calibrated, low lamp, iris open: out of detection range
Sony VPL-VW90ES, calibrated, no iris: 0.02 lux
Sony VPL-HW30ES, calibrated, high lamp: 0.08 lux
Sony VPL-HW30ES, calibrated, low lamp: 0.04 lux
Sony VPL-HW30ES, calibrated, low lamp, dynamic iris: 0.01 lux
Sony VW95ES, calibrated, high lamp: 0.02 lux
Sony VW95ES, calibrated, low lamp: 0.01 lux
So the X70's black levels are technically "half" those of the Sony, but in practice, it's splitting hairs :-)