1. A computer-implemented method comprising: executing, on a processor of a host computer system, a software publisher trust extension application, the executing including: determining a software publisher of an unknown application, wherein the unknown application is an application without an assigned reputation; determining reputations of respective ones of at least one user of software published by the software publisher, wherein individual respective reputations of ones of the at least one user being either a first reputation of normally having malicious software on a computing system of the user or a second reputation of not normally having malicious software on a computing system of the user; determining whether the software publisher of the unknown application has a reputation, the reputation of the software publisher at least including aggregated user reputations of users of software published by the software publisher including the previously determined reputations of the at least one user of software published by the software publisher; and assigning said reputation of the software publisher to said unknown application upon a determination that said software publisher does have the reputation, wherein the reputation of the software publisher includes a number of applications published by the software publisher and a number of the published applications including malware, and the assigning of the reputation changes the unknown application to a known application.