One of the quickest ways to find out information about your installed solutions is to use PowerShell.  To do this, login to one of your WFE’s and open SharePoint Management Shell.  Then, type in the following command: Get-SPSolution | Export-Csv C:\DeployedSolutions.csv.  Open this file on your local machine (or whichever has Excel installed) and dissect as needed.

This will return a fairly good amount of detail regarding your current solutions including but not limited to:

• Solution Name
• When/where deployed
• Version
• Status

Enjoy!