Checking apps for a "GateKeeper" Developer ID?
If you have the developer tools installed, you can view the signing information for a binary using this command:

codesign -dvvv &lt;path to app.app&gt;


The output looks like this:

Executable=/Volumes/Big Disk/F376/Projects/&lt;My App&gt;
Identifier=&lt;My Bundle ID&gt;
Format=bundle with Mach-O thin (x86_64)
CodeDirectory v=20100 size=3958 flags=0x0(none) hashes=189+5 location=embedded
Hash type=sha1 size=20
CDHash=761b0d1XXXXXXXXXX0dc8dd42e38eb445fb5341f
Signature size=8504
Authority=Developer ID Application: XXXXXX
Authority=Developer ID Certification Authority
Authority=Apple Root CA
Timestamp=May 7, 2013 3:07:59 PM
Info.plist entries=30
Sealed Resources rules=4 files=128
Internal requirements count=1 size=224