By the looks of the Gallery site, You may have a wait for integration:
http://codex.gallery2.org/Gallery3:Features
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Secondary Features
These are features that will probably not be part of the core Gallery 3 product, certainly unlikely to be in the initial release. We moved these off the high priority list because we felt that they were not actively used by 80% of our users. This does not mean that we don't want these features in the product; several of these features were hotly contested by our core developers and it is highly likely that those will be implemented for the 3.0 release, but they may not be part of the core bundle that users initially download.
This list exists so that when we're building Gallery 3 we can make sure that we make it possible (and hopefully very easy) for 3rd party developers to contribute these features in the future.
1. reupload: replace an existing photo with a new one, leaving the metadata intact
2. sitemap: see sitemaps.org
3. integration / advanced editing: ?? .....