PHP: 7,095,691 Domains, 1,046,426 IP Addresses
Source: Netcraft
There has been some shakeout in the large-scale shared hosting space related to the .com crash and combined with some routing issues in Germany which caused 5-10% of German servers not being able to respond to the Netcraft queries. This hurt the PHP total domain numbers a bit in recent months, but they appear to be back up nicely as of November's numbers.
You can also see how popular PHP is relative to other Apache modules at . Spoiler: PHP is the most popular.