Wow! I remember this thread. I feel so old ,'/

This is how I do it with AutoHotkey.
Save the code below as something like "MyGroupName.AHK" file (it's just a renamed .txt file) and place Win7AppId1.1.exe into the same directory as the "MyGroupName.AHK" file.

Edit the file in a text editor and change the list of applications to your own applications shortcut files. Remember, you're pointing to the application shortcut .lnk file, not the actual .exe

Save the script and then run it. It will process all the shortcuts to be grouped in "Random_Group" next time you open the shortcut.

#NoEnv ; Recommended for performance and compatibility with future AutoHotkey releases.
SetWorkingDir %A_ScriptDir% ; Ensures a consistent starting directory.

AppId(lnk){
app:="Win7AppId1.1.exe"
group:="Random_Group" ; Name for the group or application
Run, %app% "%lnk%" %group%,,hide
}

; Add shortcut links to the applications that will be grouped
AppId("C:\Documents\Menu\Start\XenceLabs_Tablet.lnk")
AppId("C:\Documents\Menu\Menu\Game\MSI Afterburner.lnk")
AppId("C:\Documents\Menu\Menu\Application\ToDoList.lnk")
AppId("C:\Documents\Menu\Menu\Audio\ROLI_Launcher.lnk")
AppId("C:\Documents\KeePass\KeePass.lnk")

Actually, if you don't use AutoHotkey, you could just do it with a batch file. Type this into a text file and save it as .bat

start "" "C:\location_of\Win7AppId1.1.exe" "C:\Users\Administrator\Application_1.lnk" "Random_Group"
start "" "C:\location_of\Win7AppId1.1.exe" "C:\Users\Administrator\Application_2.lnk" "Random_Group"

I've been using a lot more hotkeys, shortcuts and scripts in my setup recently so WinAppId fits perfectly into my workflow! The .lnks have all been set up and it's working great! Thanks so much!

How about at least a basic implementation using fullpath to .exe and window class (maybe even window names with regular expression)? Have it read/write an .ini, doesn't have to be automatic, I'm sure users will be willing to enter the details manually!
e.g
[Group_Name]
1, %ProgramFiles%\App1.exe, MozillaWindowClass, .* - Firefox
2, E:\Games\Steam\Steam.exe, USurface_.*, Steam|Friends|Downloads
3, %WinDir%\notepad.exe

I have 6-8 utility apps that I always group into a random group. I've been manually grouping them for about 4 years now, but I'm tired of it! I'm going to try your win7appid suggestion :D