You can do that like I do, with pages:
So 2008 is the 2008-galleries and 2008-personal-galleries are two albums.
The things inside are galleries.
Also you can play with tags (thing that I will do from the beginning of 2009) to "separate" galleries from the category they rapresent.
Like a picture of a flower in the "2007 - california" gallery that can be tagged "nature".
No reason to "add another level" when you have:
It's the same for wordpress with pages+category, you can do everything with this structure.
Hope that Alex agree ;)