According to a report by Finjan, Opera is used on 3% of a recently discovered botnet consisting of 1.9 million malware-infected PCs.
While a "fun" fact in itself, this number actually confirms the global Opera usage figure reported by StatCounter. However, the botnet figures have a much higher usage share for IE, and lower for Firefox, than StatCounter reports.
Again, we should remain skeptical of browser statistics because of all the error sources that exist. The botnet figures are very interesting, though, because the methodology is obviously very different to that of StatCounter and other browser statistics companies.
It does indicate that Net Applications's <1% for Opera must be way off, if nothing else. And yet, journalists and bloggers repeat the numbers from Net Applications without batting an eye.