Comment 5 for bug 971098

By default on a refresh oneiric installation, the systray-whitelist does not contain 'all' so the psensor systray icon is not visible. I guess the installation of a package has added 'all' in your case or you have forgot that you have set it manually.
Anyway, this usecase must be handled properly by psensor, a fix is on progress.

Thanks for the report and additionnal information.