We at Open Source Matters love it when people talk about Joomla!, build businesses around Joomla! and produce products that make life better for Joomla! users and developers. We do, however, have a trademark, which we are obliged to protect. The trademark gives us the exclusive right to use the term as the name of websites, services, businesses and products. Although those rights are exclusively ours, we are happy to give people permission to use the term under certain circumstances.
The following is a general policy that tells you when you can use the Joomla! name without need of any specific permission from OSM:
First, you must make clear that you are not Open Source Matters, Inc. or the Joomla! project and that you do not represent Open Source Matters, Inc. nor the Joomla! project. A simple disclaimer on your home page is an excellent way of doing that (You can find our disclaimer here).
Second, you may not incorporate the Joomla! name or logo into the name or logo of your website, product, business or service.
Third, you may use the Joomla! name (but not the Joomla! logo) in descriptions of your website, product, business or service to provide accurate information to the public about yourself. You may not imply any endorsement by Open Source Matters, Inc. or the Joomla! project.
Fourth, you may not use the Joomla! logo.
If you would like to use the Joomla! name or logo for any other use, please submit a ticket and we'll discuss a way to make that happen. We don't have strong objections to people using the name for their websites and businesses, we just want to have a chance to review such use. Generally, we approve your use if you agree to a few things, mainly: (1) our rights to the Joomla! trademark are valid and superior to yours and (2) you'll take appropriate steps to make sure people don't confuse your website for ours. In other words, it's not a big deal, and short conversation (usually done via email) should clear everything up in short order.
If you currently have a website that is using the Joomla! name and you have not gotten permission from us, don't panic. Let us know, we'll give you permission, as described above.
Note that licenses for name or logo use will not be given for businesses or products that violate the GNU GPL (under which Joomla! is distributed).