The digital distribution of video games is apparently growing by leaps and bounds. According to GfK Chart-Track director Dorian Bloch, digital game sales for the PC could total more than $1 billion for this year.

Bloch estimates that digital PC games sales for 2008 were about $600 million. Why so hazy on those numbers? Well, the thing is, a lot of publishers don't offer up digital sales numbers for their games. Even games services like Steam and Direct2Drive, who reveal their best-selling games on a weekly basis, are reluctant to release actual sales numbers. It makes it tough for the scope of digital distribution to be effectively measured.

"This is a huge business," Block said at the Develop Conference in Brighton (via GI.biz) "The key thing for me in this is that these publishers support me in what I do and they want their sales included in the charts."