What other PHP memory_limit restrictions could there be besides php.ini? I have been facing some weird memory limit issues on a managed dedicated server and spent alot of time trying to fix this other with the server admin. phpinfo() is showing the correct overridden memory_limit values.
Everything is cool, except when I use drush to do drush en module or Views Bulk Operation execution. If anyone has experienced this before, I will really appreciate if you can share with us the steps needed to fix this.

In my php.ini :memory_limit = 256M ;

In sites/default/settings.php: ini_set('memory_limit', '256M');

The WSOD message after executing a Views Bulkd Operations on ONE entry:
Fatal error: Out of memory (allocated 131334144) (tried to allocate 5 bytes) in /public_html/includes/cache.inc on line 401
Memory used at: devel_boot()=5.02 MB, devel_shutdown()=82.06 MB, PHP peak=82.25 MB.

In SSH, using drush cli. After running drush en languageassign:
The following extensions will be enabled: languageassign
Do you really want to continue? (y/n): y

Fatal error: Out of memory (allocated 76021760) (tried to allocate 72 bytes) in /public_html/sites/all/modules/views/includes/base.inc on line 84

Drush command terminated abnormally due to an unrecoverable error.                      [error]

Error: Out of memory (allocated 76021760) (tried to allocate 72 bytes) in
/public_html/sites/all/modules/views/includes/base.inc, line 84
Try including "RLimitMem 128000000" in your .htacess file.