There has been a mail thread on the seam-dev list that eventually broke down into a discussion about the editor component and using different converters to support different wiki text markup. We wanted to move the conversation here since it is RichFaces specific.
This jira summaries some of the higher level items https://jira.jboss.org/jira/browse/RF-6452
In general the editor component supports various converters. New converters == new formate support. At the moment there are not examples of this other than "useSeamText" attribute that under the covers switches to a seam text converter.
So some examples need to be created and posted - such as textile http://www.textism.com/tools/textile/
There is also the open question about the use of the "useSeamText" attribute. It really seems to mean "useConverter" in which case we don't need it since we should be able to set the converter and then just use what is set. If we keep with that behavior we would end up with "useTextileText" and "useXXText" which gets messy.