I spent a few minutes trying to figure out what Lift is but didn't get enough information scent from the introduction to persevere. I did pick up that Lift is not too interested in solving any persistence problems.

For what I'm working on (multiplayer, offline/online web application) persistence has taken the most work to get right. It has to be done at the framework level. An offline web app has to deal with synchronization (backporting of data, client-side data loss or corruption, client-side clock issues, GBs of data per user, multiple users sharing the same data), client-side and server-side migrations (code, data, schema), browser-side database (indexing, memory usage) etc.

Partition-tolerant persistence is almost exactly what I'd want a web app framework (as opposed to web site framework) to be tackling. I'm not aware of any frameworks (including Backbone, Lift, Rails etc.) that do.