I'm pretty sure if Mac OSX or Linux gained 2% of the market, everyone would go apeshit.
However, it's somehow unimpressive for IIS. Go figure.
Yes, all Linux and Mac people are idiots. Duh.
The difference from 31% to 33% is nothing compared to the distance from 4% to 6%. The numbers may be the same, but a 50% increase is much more impressive than a 5% increase.
Calling 4% to 6% an achievement seems to be grabbing at straws to me, it may technically be a 50% gain but when you actually look at the numbers they're both equally impressive.
I hold Mac/Linux in the same position I hold IIS and Apache. They both have an uphill battle and they both are progressing at a slow rate. Recently however, IIS has shown a much more accelerated growth when compared to Mac OSX which has stagnated in growth (rougly a 1% over the course of a year if I remember correctly) and even more recently gone down in usage by half of a percent.
I'm sure if Apache were in the situation IIS is in, and Apache made these gains there would be much more fanfare then there is for IIS. It all boils down to the mindset that OSS=Good MS=Bad.