A blogging platform based on Rhino (EcmaScript) on JVM hosted on virtualized server (or in cloud) would easily resist slashdot effect.
And using file-based storage it would be storage-friendly, too.
And nobody prevents you from using external editor for WordPress, even.
(Answer: hope your filesystem updates the directory change time when a file inside changes, or that your app server is inotify-ed of the change. Both are more complicated than querying a database.
If I used KiokuDB for Angerwhale, it would only take me one key lookup for things that currently involve traversing the directory tree. Caching is nice, but it is not the solution to all problems.)
Timestamps help alot if you're paranoid, also.
How many hits per second is slashdot effect? We could count.
I think slashdot effect mostly happens because database (mysql, generally) locks down, and we're removing that bottleneck by going into file-based storage and in-memory caching.