We’re seeing this issue as well on blogs running WordPress 2.6.x and using Twitter Tools 1.2b1, 1.5b2 & 1.5b3 (on two different servers). Some were working before (using the old version 1.1b1) and just stopped updating while the others that started out as 1.5b2 installs have never pulled the Twitter posts and only return “No tweets available at the moment.”
So, we’ve deactivated the plugin, went into the database and removed the wp_ak_twitter table, removed the “aktt_” rows from the wp_options table, reactivated Twitter Tools 1.1b1 and it is working again.
While we hate to lose the new functionality of the 1.5 line, there’s something that’s not working correctly on our setup.