I like the growing trend of publishing tech books on-line as constant works-in-progress, encorporating reader feedback and then shipping "builds" that are basically point-in-time versions of the text in PDF, Web or paper formats. A wholesale community of readers testing/debugging the text as it is developed. Very 21st century. Very Web 2.0.
This turbogears book springs to mind as does this django book. Both books will be better by the time they hit 1.0 as a result of the FDW approach taken to their creation.
TurboGears appears to be waaayyyy better than django in one vital aspect. It has the best set of doodads. A new trend I wonder? What do you mean your application does not have its own cute doodad? How 20th century! How Web 1.0 of you!