We decided to publish a little editor tool to simplify grouping of objects inside the hierarchy. It does create an empty game object and places all the selected objects inside. You can also ungroup the items again. The tool uses the standard shortcuts for grouping (Ctrl+Shift+G for PCs or Command+Shift+G on a Mac) and ungrouping (Ctrl+Shift+H for PCs and Command+Shift+H on a Mac).

Check out our video for a little demonstration:

You can find the tool in the asset store.
Happy grouping!

Edit:

A tiny update for requested features has been posted today (5/8/12) in the asset store…
Version 1.2:
– Changed the group wizzard into an editor window
– Replaced the tag option with a tag drop down menu
– Added option to center the group relative to the selected objects
– After grouping automatically select the group object