FYI, there is definitely something weird going on with Twitter Digest with respect to putting tweets in the correct 24 hour period. My gut says Twitter has changed something in the feed, b/c the plugin has worked flawlessly for me until today. I will investigate and issue a fix ASAP.
Update: I’m not sure if it is Twitter’s fault for changing something or not, but there is definitely an issue in the plugin when it comes to dealing with time zones properly. A fix is forthcoming.
Update 2: The latest version of the plugin has been released. See http://wordpress.org/extend/plugins/twitter-digest/. Tweets should now be displayed using the GMT Offset option value in the WordPress ‘General’ settings. If you Twitter ‘Location’ is the same as the GMT Offset, then the times in your post should match the times in your Twitter feed. Please let me know if they don’t.