http://www.scienceagogo.com/news/20070229005112data_trunc_sys.shtml

It can't be 70 meters. If the sheet has an area of a million square kilometers and is one kilometer thick (I think it's less than that), then sea levels would rise by 2.8 meters. So, I think it is more like 70 cm. You need to melt all the ice in Antarctica to get 60 meters sea level rise.

I found these
http://www.faqs.org/faqs/sea-level-faq/
http://en.wikipedia.org/wiki/Sea_level_rise
http://www.grida.no/climate/ipcc_tar/wg1/412.htm#tab113

Which substantiate the number.

I was surprised but it may well be real given the calculations of the antarctic ice on Mars being able to cover the planet to a depth of 36ft. if it melted.