Use permanent links (URLs) as addresses for your albums and items.
One of the nice and bad aspects of G1 was that the namespace of albums was flat: you couldn't have two albums named the same within the same gallery. G2, with its truly hierarchical albums, fixes this, at the expense of those nice short descriptive URLs: URLs in G2 are either very long or meaningless (with the rewrite module).
Example of an original URL:
http://www.example.com/gallery2/main.php?g2_itemId=5471
Example of a normal short URL:
http://www.example.com/gallery2/v/Countries/Switzerland/Zurich.html
With Permalinks, you can have the best of both worlds: short descriptive URLs for some of your albums (and even any other item) which have the added benefit of not changing if you move an album into a different parent album.
Example of a permalink URL:
http://www.example.com/gallery2/f/Zurich
After activating the module, you need to enable the corresponding URL Rewrite (the URL Rewrite module also needs to be enabled, using either "Apache mod_rewrite" or "PHP pathinfo"). Once that's done, you can define a Permalink for any item in that item's edit interface. You can then access the item using a short URL that doesn't depend on the item's location. The URL is build from the gallery-base-URI, a fix path (default "f/") defined in Site-Admin section Permalinks (see above) and the Permalink defined for the item ("myitem" in the example).
Example using the "Apache mod_rewrite" option:
http://www.example.com/gallery2/f/myitem
Example using using the "PHP pathinfo" option:
http://www.example.com/gallery2/main.php/f/myitem
Some more explanation: