This could be easily solved by adding this plugin:
http://www.spooky-possum.org/callum/software/index.html#db-calculator
to the default configuration :)

Oh, I think that the plugin should to the package since its an useful general-purpose plugin that I believe many will find useful.

Also, most people don't know you can use plugins, and if they do, they don't know where to find them, the internet is so big. I didn't know that address.

It's already available, and installation becomes easy once a proper Capuchin repository is setup for Deskbar. This will happen till the final 2.24 release.

If I understand correctly, this bug was about installing the plugin by default. What are arguments against this? 

If Gnome is about carefully choosing default configuration (to make out-of-the-box experience the best), I think this is a way to improve it.

Your right, included a math module by default would increase the power of Deskbar. I have to check in which shape the module is, what dependencies it has and finally ask the originally author's if it's okay with them to include the module.

I looked at the code and talked to the authors of the module. Everything looks fine. The module will be added to svn trunk in the next couple of days.

I added the module to svn trunk. It will be part of 2.23.4.

*** Bug 344377 has been marked as a duplicate of this bug. ***