This is a nice article on the offline sync feature of LiveCycle Data Services 2.6 - AIR Data Synchronization via LiveCycle Data Services ES 2.6. It was written by John C. Bland II.
I worked on this feature for LCDS 2.6 (which by the way just got released last week). The SQLite DB built in to AIR is really nice to work with and the Actionscript APIs for using it were nicely designed by Jason, one of my coworkers here at Adobe.
I think the offline feature is pretty neat. There is still lots of room for improvement, but the basics that we do have are pretty powerful. We are in the planning stages for the next LCDS release and I expect that improving our offline story, particularly for AIR, will be on the list.
Check it out!