Thunderbird for Solaris/ OpenIndiana x86 is available since some time, but I'm
also using lightning ( the calendar plugin ), which is not running, even when
patching the version in install.rdf.
But today I found a new plugin in the download folder for 1.1 which is
compatible with Thunderbird 9.0.
But currently there is also thunderbird 9.0.1 available, which I have running
here on OpenIndiana and the lightning plugin doesn't work.
But just unzip the xpi-Archiv, patch the maxVersion in install.rdf from 9.0
to 10.0 and you can install the plugin also on version 9.0.1 of thunderbird
and it shows the calendar.