Then XProtectPluginChecker is the status menu app for you!
Written in BASH, sprinkled with PlistBuddy/awk/sed-Fu with a dash of mdfind magic, and wrapped with Platypus, the aim is for XProtect Plugin Checker to be able to dynamically accommodate any additions Apple might make to the Plugin Blacklist, although only Flash and Java seem to be in their crosshairs right now, who knows? Silverlight might be next, given its lack of updates (going on 10 months).
A bonus idea for making this more useful is to make a launchd script that watches the XProtect plist file(s) then fires off the XProtectPluginChecker script when they change, emailing the results to you, because knowing is half the battle!
If you find this useful or if you have some hiccups with it, let me know. UPDATE: Now with comments enabled! :]
Also related, myXProtectStatus is a similar style menu status script that lists the malware threats Apple is blocking.