If you want to have your CPU temperature on your desktop without having to load some system monitoring tool like Gkrellm or other programs you can use the Gnome sensor-applet from http://sensors-applet.sourceforge.net/ you can download it and install.
To download you can use this depending on your distribution:
apt-get install sensors-applet
yum install gnome-applet-sensors
The advantage of using the yum or apt-get format is that it will install all dependencies, you can also download the source and compile your self.
After you install it you can add the applet to your panel and have it show on your desktop. They will look like this:
It not only will give you the ability to see the temperature values but also set alarms and trigger some programs or scripts.
On of the key features for me it was that it support reading the temperature of my old Toshiba A75 notebook, where the sensor library does not work. It does that by supporting the old omnibook standard, but as always to add that support to my Fedora 10 have to figured out what version of omnibook will work and since it is and old standard most of the omnibook libraries are old and supporting old kernels, so here is what work for me:
There are two projects on SourceForge.net for this http://sourceforge.net/projects/omke/ and http://sourceforge.net/projects/omnibook/ the omke project has a kernel module that did not compile with my kernel (126.96.36.199-170.2.68.fc10.i686) but the omnibook project did work only if downloaded sources from the trunk version, the release version did not work. So here are steps to download the SVN version:
You will need svn if you don't have it use yum install svn.
svn co https://omnibook.svn.sourceforge.net/svnroot/omnibook omnibook
after that you will need to execute as root or a sudo user
Now your sensor-applet will be able to read your cpu temp
You can also install this two scripts komnibook and omke scripts they will be used to generate a configuration and manage you omnibook notebook. They are here http://sourceforge.net/project/showfiles.php?group_id=48623
Good look and enjoy!