Apple’s invasion of the workplace continues apace even as it has gone sort of unnoticed…until now. Forrester Research’s  Global Tech Market Outlook for 2012 and 2013 has some numbers that tell Apple’s success story. Apple sold $2 billion worth of iPads to business and government in 2010. It sold $6 billion in 2011, and is forecast to sell $10 billion in 2012. A guess for 2013: $16 billion. Impressive. Great credit must be given to the iPhone, whose users brought it to work and demanded that IT support it. The iPhone cracked the door open, and the iPad is rushing in. At the same time, the iGadget halo is spreading out to cover Macs as well. Forrester forecasts that enterprise sales of Macs, which were at $2 billion in 2009 (and $61 billion for Windows PCs), will grow to $9 billion in 2012 and $12 billion in 2013. In other words, Apple’s share of devices in enterprises will grow from 8 percent in 2010 to 29 percent in 2013, and that’s pretty incredible. "The Apple assault on the corporate market has so far taken place without much formal Apple support, and probably without Apple itself understanding its full extent," Forrester analyst Andrew Bartels wrote in the report. "That's because corporate adoption of Apple products has been largely clandestine." It sure has. And how are iPads being used in the office? Here’s a slideshow that counts the ways.