I just installed it from the dungog repo with no problem, using the updated
yum --enablerepo....
My system seems to have already had gd installed (at least I have it installed, and /var/log/yum/yum.log does not say I just installed it...)
You could try simply installing gd using
yum install gd or
yum --enablerepo=dungog install gdOr, as with any yum problem, try
yum clean all, then try to install again.
[edit]
On a more 'virgin' SME 7.2 system I found that I did
not have gd installed.
yum install gd found it in the 'base' repo - so you may want to make sure that your yum repository configuration is correct. Unless you installed SME 7.2 from CD on brand new hardware you need to update your yum repository configuration if you haven't already done so as shown in item 2. of the 'Yum Update' instructions here:
http://wiki.contribs.org/Updating_to_SME_7.2#Yum_Update. After resetting your yum repositories, you will have to re-add the dungog repository.
[/edit]