Professional PHP

Nexen has some statistics about PHP version adoption (via PHP Developer). It shows PHP 5 usage at 1.5%, less than the current usage of php 3 at 1.9%. It seems like people are keeping somewhat up to date in the 4.x line, at least by the 79% adoption rate of 4.3. Sadly, it 4.1.2 seems to be the second most popular version. Are these hold outs due to register globals? Sourceforge only recently upgraded from 4.1.2 to 4.3.9, choosing not to move to PHP 5, even though it was available.

This is a chicken and egg problem. Applications cannot leave php 4 behind until a critical mass of hosts support 5. yet, the hosts cannot leave php 4 behind until there are backward compatibility and stability assurances as well as demand created by popular applications moving to php 5.