I just went to upgrade PEAR on a CentOS 4.4 server and had problems.  The installed PEAR version (from pear info PEAR) was 1.3.2, but when I ran ‘pear upgrade PEAR’, I was told that I needed PEAR version 1.3.3.   The solution: ‘pear install PEAR-1.3.3’ to upgrade to that particular version.  Then I could ‘pear update PEAR’ which brought it up to version 1.5.3.     Then I could run a ‘pear upgrade-all’ to update all of the other packages.