If you have installed one or more packages that do not have an associated repository, those packages will never be updated. The same is true for packages that used to have an associated repository and no longer do -- for example, the repository has disappeared off the Internet, or it still exists but no longer contains that package, or you have removed it from your sources list.
Someone interested in security and/or compatibility will likely want to remove or replace as many of these packages as they can. But Ubuntu Software Center currently offers no way to see which packages on your system are in this state. I *think* Synaptic's "Installed (local or obsolete)" Status filter is supposed to do this, but I can't tell for sure.
This has long been specified but is not yet implemented <https://wiki.ubuntu.com/SoftwareCenter#channels>: "“Installed Software” should have child items for each source from which any software is currently installed, plus an item containing all installed packages with an unknown source ... the section for packages with an unknown source should have a question mark as its icon, and the label “Other”."
[Originally reported by Neil Patel in <http://twitter.com/njpatel/status/16551486084>.]
Hey mpt! Thanks for your report. The display of child items for the "Installed Software' view is one of the items scheduled for implementation for Maverick in the "Software Center UI Enhancements" blueprint:
https:/
It's currently included in the work items for Alpha 2 and I've started the work in a branch, so the plan is to have this feature by the end of the week.