Description of problem:
php 5.1.2-5 depends on postgresql-libs.
Should this not be the responsibility of php-pgsql?

Example 'yum install php' output:

Installing:
php                i386       5.1.2-5         core           3.5 M
Installing for dependencies:
apr                i386       1.2.2-7.2       core           121 k
apr-util           i386       1.2.2-4.2       core            74 k
aspell             i386       12:0.60.3-5     core           959 k
aspell-en          i386       50:6.0-2        core           1.6 M
curl               i386       7.15.1-3        updates        265 k
httpd              i386       2.2.0-5.1.2     core           1.1 M
libidn             i386       0.6.2-1.1       core           191 k
php-pear           noarch     1:1.4.6-2.1     updates        351 k
postgresql-libs    i386       8.1.3-1         core           193 k