For bug reports and feature requests please see, if it is already reported on the list of open bugs. If not, report it. Also see the Contribute section for instructions on bug reporting.
For general questions, comments or suggestions you might use the Chameleon skin talk page on MediaWiki.org. For direct contact with the author please use the Email functionality on MediaWiki.org.
Finally there are the MediaWiki IRC channel (Server: freenode.net, Channel: #mediawiki) and the MediaWiki mailing list.