Another feature I really like is that the Develop workspace now includes the Collections panel.

All Adobe have really done here is to take one logical step further from Lightroom 2 where the panel was made available in the output workspaces, Print, Slideshow and Web. Making Collections more readily available is a quick win, and sadly Collections are still underpowered, but it's still a very welcome step and is another incentive for getting yourself out of the rut of using folder-based ways of organising your pictures.