It's a bit early for the big music companies to start panicking, but it looks like the heyday of double-digit growth in digital music sales may now be behind us. That's according to market research firm Nielsen, at least, which found that sales in the US fell flat in 2010 after a 13 percent increase from 2008 to 2009, and a whopping 28 percent jump from 2007 to 2008. Nielsen is quick to point out, however, that it thinks this is a "plateau," and that it "doesn't mean that this digital consumption is going to drop significantly." It also still seems to be a different story outside of the US, with Nielsen reporting that digital music sales were up up 7 percent
