From the paper:
When a function stub is hit at runtime, if there is no locally cached function closure, download the function code using helper function blocking download, apply eval to it, ... cache the resulting function closure locally ... [and then] apply the locally cached closure and return the result.
As Web applications add more and more functionality to try to match their offline competition, their code will become bigger and bigger, and techniques like Doloto are sure to be necessary.
On a related note, if you have not seen Yahoo Steve Souders' work on exceptional performance for Web 2.0 sites, you definitely should. What makes Steve's work so compelling is that it correctly focuses on the user experience -- the delay a user sees when trying to view a web page -- and not the server-side. Because of that, much of his advice and the YSlow tool look for ways to reduce the size of the download and number of connections needed to render a web page.
Update: About two years later, Doloto becomes publicly available.