I just tried, and though exclude is not included in the /etc/yum.conf, it can be added and will work.
Code:
exclude = evolution*
gnome-pilot*
pilot-link*
*beagle*
openoffice.org-langpack*
libmal
yum check-update
Loading "installonlyn" plugin
Setting up repositories
updates [1/4]
updates 100% |=========================| 951 B 00:00
core [2/4]
core 100% |=========================| 1.1 kB 00:00
macromedia [3/4]
macromedia 100% |=========================| 951 B 00:00
extras [4/4]
http://mirror.clarkson.edu/pub/distr...ta/repomd.xml: [Errno 14] HTTP Error 404: Date: Mon, 08 May 2006 22:19:52 GMT
Server: Apache/2.0.52 (Red Hat)
Content-Length: 348
Connection: close
Content-Type: text/html; charset=iso-8859-1
Trying other mirror.
extras 100% |=========================| 1.1 kB 00:00
Reading repository metadata in from local files
primary.xml.gz 100% |=========================| 313 kB 00:02
updates : ################################################## 1000/1000
Added 0 new packages, deleted 12 old in 1.62 seconds
primary.xml.gz 100% |=========================| 958 kB 00:06
extras : ################################################## 2670/2670
Added 155 new packages, deleted 580 old in 5.80 seconds
Excluding Packages in global exclude list
Finished