A great summary of the Get Info command (properties) from Tiger:
… In versions of OS X prior to 10.4, if you selected multiple items in the Finder and hit Get Info, you’d get a nice summary window showing the size of the items in the Finder selection. In 10.4, however, that behavior has changed, with (of course) an exception. If you select 10 or fewer items in the Finder and hit Command-I, you’ll get (up to) 10 distinct Get Info windows. This change is a welcome one, for it makes comparing more than one file or folder quite simple.
If you select 11 or more items in the Finder and hit Command-I, you’ll get the 10.3-style Multiple Item Info window—a single window containing summary information for the selected items…
… If you want to see the summary info window for any Finder selection, regardless of the number of items in that selection, hold down the Control key, and then pick File -> Get Summary Info.