This is a synthetic property that was added in V3: http://blogs.msdn.com/b/powershell/archive/2012/06/14/new-v3-language-features.aspx
You can now use Count or Length on any object, even if it didn’t have the property. If the object didn’t have a Count or Length property, it will will return 1 (or 0 for $null). Objects that have Count or Length properties will continue to work as they always have.
PS> $a = 42 PS> $a.Count 1