Last time that I tried the wp-cache plugin for WordPress, it caused errors when retrieving cached pages; after some investigation, it appears that my hosting provider is likely the cause, but I found a mod to wp-cache that makes it work (and no, I’m not a regular reader of that site, I found it linked from the WordPress forums).
If you experience any problems, let me know. Of course, if you do experience problems, you probably won’t be able to read this post…