A couple of months ago we highlighted the low numbers of sites migrating to Apache/2.0, and contrasted it with the speed at which site administrators adopted Apache/1.3.26 which contained a fix for a potential buffer overflow problem.
If anything more surprising is the slow adoption of new versions of Sun's Solaris operating system. Solaris 9, released in May this year, is running on fewer than 1000 web site ip addresses found by the September survey, and there are roughly twice as many sites running Solaris 2 & Solaris 7 as are running Solaris 8, released in March 2000.
Historically, slowness to gather upgrade revenue has usually been a portent of trouble to come for web technology vendors, and the figures coincide with Sun's difficulties generating revenue and profits over the last eighteen months. By contrast, Windows .Net Server, which is not yet scheduled for release, has almost as many as ip addresses as Solaris 9, including some impressive, high volume sites, such as Nasdaq.
Sun would reasonably point out that their boxes typically cost a lot more, and the upgrade cycle for more expensive kit could be expected to be slower.