After many, many attempts to pull in some of our Solaris servers into OpsMgr, we finally logged a call with Microsoft, and discovered that KB2585542 is the culprit.
Errors returned during discovery could range anything from OpenSSL not installed to this wonderfully cryptic error:
<![CDATA[Debug: Logging to file 'C:\Windows\Temp\InstallElevatedAgent.vbs.log'
Executing command: echo -e mail=\ninstance=overwrite\npartial=nocheck\nidepend=quit\nrdepend=quit\nconflict=nocheck\naction=nocheck\nbasedir=default\n > /tmp/scx-$USER/scx;uncompress -f /tmp/scx-xxxxx/scx-1.0.4-248.solaris.9.sparc.pkg.Z
To resolve, simply uninstall this hotfix, reboot and run your discovery again.