How the biotech manipulates GM cultivation figures

Friends of the Earth published their 2009 copy of their report "who benefits from gm crops?" and that's certainly worth reading (report, summary).
Over the years there has been criticism about the cultivation figures published annually by ISAAA because Clive James repeatedly has refused to give information about where these numbers are coming from while they are continuously refered to as the only available source for GM acreage worldwide. Not surprisingly ISAAA saw an increase in 2008 again, speaking of a "historic milestone"
However, FoE come to a very different conclusion when they reviewed the last ISAAA report as well as figures given by EuropaBio. ISAAA increased the acreage it reports by simply multiplying each hectare by the number of GM traits grown on it. So a hectare of Bt maize is a hectare of GM cultivation, but a hectare of Bt maize with herbicide tolerance adds up to two hectares - at least in the eyes of ISAAA. So if all agricultural land would be grown with triple-stack crops, we suddenly would have three times as much agricultural as before?
EuropaBio also shows some interesting calculations for the GM acreage in Europe and the EU. In their comparison between 2008 and 2007 they simply excluded France. France had grown some Bt maize but that got banned in 2008. In most peoples eyes that would be a decrease in acreage. Not so for EuropaBio. At the other hand however, they have no problem of including 3000 hectare of Bt maize cultivation in Poland, even though here the cultivaton is done illegally. Another country, that leads to creative counting is Romania. Until 2007, the country was growing GM soy but the cultivation stopped when the Romania entered the EU. So for Europe as a whole, the cultivation stop in 2007 clearly brought a huge reduction in acreage. Where EuropaBio claims an increase of in the EU of 21% from 2007 to 2008, Foe comes up with very different figures.
"What the figures really say: 35% decrease in Europe over 4 years, 2% decrease in 2008 for the EU." and in total: GM crops (or specifically MON810 maize) are only grown on 0.21% of the agricultural land in the EU.
For more details: please read the FoE report