Did you just run into a download or a file on your computer that is digitally signed by Plantronics? If that's the case, please read on.
You will typically see Plantronics when running the file. The publisher name is then displayed as the "Verified publisher" in the UAC dialog as the screenshot shows:

You can view the additional details from the Plantronics digital signature with the following procedure:
Here's a screenshot of a file digitally signed by Plantronics:

As you can see in the screenshot above, Windows reports that "This digital signature is OK". This means that the file has been published by Plantronics and that no one has tampered with the file.
If you click the View Certificate button shown in the screenshot above, you can view all the details of the certificate, such as when it was issued, who issued the certificate, how long it is valid, and so on. You can also see the address for Plantronics, such as the street name, city and country.
VeriSign Class 3 Code Signing 2010 CA and VeriSign Class 3 Code Signing 2009-2 CA has issued the Plantronics certificates. You can also examine the details of the issuer by clicking the View Certificate button shown in the screenshot above.
These are the Plantronics files I've collected, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 0/56 | PLTHub.exe |
| 0/70 | optimus3D_x64.exe |
| 0/46 | GameCom780.exe |
| 0/54 | GameCom780.exe |
| 0/54 | CMEFFECTAPO_RIG5020.dll |
The detection percentage is based on the fact that I've gathered 280 scan results for the Plantronics files. 0 of these scan results came up with some sort of detection. If you like, you can view the full details of the scan reports by examining the files listed above.
The analysis is based on certificates with the following serial numbers: