I do not know where we are supposed to document this stuff, but when we do figure that out, here's a description of the steps I undertook to verify that JSPWiki was not a previously registered trademark in the US and EU:
On 26 May 2009, Andrew Jaquith determined that JSPWiki was not a registered trademark in the United States. To do this, he searched the Trademark Electronic Search System (TESS), operated by the United States Patent and Trademark Office (USPTO). The term he used was JSPWiki, meaning that "JSPWiki" could appear by itself, or as a prefix or suffix to another trademark. The search was performed for live and dead terms, for for all fields: owner name and address, serial number, and combined word mark. No matches were found. The lack of matches means that the USPTO has no records of JSPWiki as a trademark. It is possible, however, that JSPWiki is used by another party as an (unregistered) service mark.
Andrew performed a similar search at the EU Office for Harmonization of the Internal Market (OHIM), at the Community Trademark Online database (CTM-ONLINE).
To verify that JSPWiki was not used as a service mark, Andrew performed a Google search for "JSPWiki" on 26 May. The first 100 hits were all related to the JSPWiki project (i.e., the Apache Incubator JSPWiki project or its predecessors). Andrew also searched Freshmeat.net and Sourceforge.net for "JSPWiki." All hits (1 and 7 hits, respectively) referred solely to the JSPWiki project, or to an extension project built with, or integrated with, JSPWiki.
In summary: the US and EU trademark searches, and the Google search, suggest that the project name JSPWiki does not conflict with a previously registered trademark.