Photosmith, the “travel-sized companion” for Lightroom, sounds quite interesting, and now the developers (who are independent of Adobe) have posted a detailed preview featuring numerous screenshots. Regarding Lightroom integration, they say:
Tag, rate, star, keyword, organize, etc, your pictures in the field. When you’re back at your main computer with Lightroom, simply start the Photosmith Plugin for Lightroom. (See this page for download and install instructions. The plugin will remain free after the app launches.)
The plugin will search for Photosmith running on your iPad, contact it for the latest statistics, and then let you choose whether you want to sync everything, or just a particular collection. Everything includes… well, everything. Even your collections and keywords are sent over to the iPad so you don’t have to recreate them if you’re out in the field.
I look forward to checking out the app when it goes on sale (hopefully quite soon).