Mac Software Business: Episode 7: Software Pricing.
I recently did a podcast hosted by Scotty from the Mac Developer Network, along with Kevin Hoctor and Alex Lindsay. We talked about pricing for our applications, as well as what to charge for upgrades and such.
I had my own questions as well (what should we charge for upgrades?). Looking at the Mac landscape, it looks like the answer is somewhere between 40%-60%. Unless you're Apple, then you charge up to 100% (iLife and iWork!)