Session alternative for plugins (due to caching)

A similar question popped at [wp-hackers] and apparently Eric Mann‘s plugin, WP Session Manager, is the way to go.

I haven’t analyzed the plugin’s code, so cannot tell about its inner workings.

Pippin Williamson embeds WPSM in his Easy Digital Downloads plugin. Given Pippin’s review and Eric being such a pro-old-timer-wp-ninja, I wouldn’t look no further. Of course, a canonical Answer in Stack Exchange standards requires a full technical spec on what goes on, but I’ll let this to another taker.