Aperture & libraries
You can export folder (in your example 2009) as a library. This self contained library can be stored where you like and once reattached it is very easy to switch libraries from within Aperture. The only shortcoming of this is that images from 2009 are only available when that library is open.
|Douaumont Ossuary by Eric 54-BNF|
from Armistice Day
|Silhouette at sunset by Jill Hancock|
from Portrait Lens (around 80mm or equivalent - please check the full rules)