I have a Sigma 17-70 F2.8-4.5 DC Macro that always shows as a Sigma 10-20 4-5.6 EX DC in Aperture 3. Since this is a more highly-regarded and pricier lens I only wish the software was accurate!
Yes, the focal length is correct, but I chuckle every time I see that the 10-20 4-5.6 lens has taken a pic @ 70mm and F2.8!
Having said that it still seems a shame that an industry that attempts to abide by standards can't get their act together on this issue. Digital asset management programs offer search algorithms to sort by many values, including the lens used. Suppose sometime down the road you want to find shots taken with that Tokina 80-400 only to discover there are none!
As far as changing the Exif data with other software I'm still waiting for a program that I can understand. I tinkered a while back with Phil Harvey's ExifTool and felt completely lost. I wish there was a front end for it, or maybe some step by step instructions that the average Joe Photographer can grasp!
Edit: latest news announced on PF Home page - "EXIF in all photos!" Nice work, Adam. Now prove to Apple, Adobe, et al and all the lens manufacturers that this info IS important to us after all.