I did a bit of analysis concerning the versioning information exposed by all extensions in 5.2.5 [the data in zend_module_entry, exposed to userland via phpversion()].
Extensions that do not expose any info at all: 46 out of 83 (the total number being calculated by counting the subdirs in /ext)
Extensions that have had some changes in the source code since 5.2.4 and did not update their version info are, afaik:
tidy (but at least the version info has been updated in the global phpinfo page)
- mysql had some changes regarding compat with mysql 3. I am not sure if it only affects build time (in which case updating version info is useless) or not
- oci extension ONLY updated version info (1.2.3 to 1.2.4) but NOT the code!
The following extensions do not provide any version info, not even in the global phpinfo page:
And last but not least, the list of extensions that do not provide version info in their zend_module_entry:
sybase_db / sybase_ct