Redmine

Maybe this could be implemented with a duplication of this description field.

One type of description field (for project list for example) and one type of "welcome message" or something like this which is displayed on the home page of the project itself instead of the project description?

Progressive Projects List plugin solves this issue and adds some other cool features.

If you just want to get rid of the descriptions in the project list, and you don't need it configurable, use the Custom CSS plugin ( http://www.redmine.org/plugins/redmine_custom_css ) with the following CSS rule:

div#projects-index div.wiki.description { display: none; }