Good news - php-xml in rhel5 provides php-domxml now - that bug is closed.
Just filed another redhat bug report suggesting a change to the php-pear rpm because: - In RHEL4 php-pear provides Archive_Tar, Console_Getopt, DB, HTTP, Mail, Net_SMTP, Net_Socket, PEAR, XML_Parser and XML_RPC - In RHEL5 php-pear provides Archive_Tar, Console_Getopt, PEAR and XML_RPC
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=218220
Hopefully Redhat likes the suggestion, but it's not a trivial one... Maybe consider it for php-pear in centosplus though.
Thanks,
Greg