Two features that have been a long time coming --
I've been flirting with the features and interface of Flicker. There is no doubt its highly polished and feature rich, but I just couldn't do the $24/year (even though its not a bad price) and give up the control and freedom of a "host-your-own" solution like Gallery. I took a quick peek at what the competition had to offer and still came back to Gallery hands down.
I really hate the enforced hierarchy of Gallery. Tags make sense for images as Flickr proves. Hopefully they put together a nice implementation.
Probably second to "Flickr-like tags" as far as number of feature requests, is more robust watermarking support. Now, you cant have a new watermark and say "apply it to all images in this album" -- you have to do it all by hand or re-upload the entire set (a serious pain).
I would expect RC-2 to appear very soon (order of weeks) with the official 2.2 release arriving around the end of March or beginning of April. The more and more I think about it, I'll probably upgrade when 2.2 RC-2 arrives so I can start playing around with the new functionality.