This occurs because 95% of IE8 here are with the "Display intranet sites in Compability View" enabled, and unfortunately, due to political issues, we can not disable it.
I've tried to apply this patch (#2621), but did not work. It would be nice to fix this...
Attachment: Piwik browser version report
If you submit a patch or pull request we may fix it, thanks!
I tried the patch again, made some changes, but without success.
This "bug" makes this report useless in intranets with IE, it is very frustrating...
Closing this one, as this is now handled by DeviceDetector