Way back in 2005 a GNOME 10x10 goal was created by Jeff Waugh at a conference in Stuttgart, Germany. The GNOME 10x10 goal was stated as "To Own 10 % of the Global Desktop Market by 2010." Well, it's now 2010 and sadly this goal did not come to fruition for the GNOME project or even the Linux adoption rate in general commanding not even close to 10% for desktop PCs.
In some specific geographical regions Linux may be controlling more than 10% of the market or for specific devices (e.g. netbooks and mobile phones), but for the global desktop market this goal was not achieved.
The notes regarding GNOME's 10x10 goal, which actually hasn't been talked about much in recent times, is available from the GNOME Live Wiki