This is, yet again, an attempt to write down a policy that's been in effect for quite a while.
All comments go to moderation. I will get around to checking the moderation queue - honestly. (OK, not all comments - administrators and certain "blessed" accounts - of which there are none - also get to skip the moderation queue.)
All comments are subject to a "lameness filter" that will reject comments based on programmatic filters. These are basically an attempt to block spam without requiring a captcha.
This policy has been in effect for a while but never officially typed up. Basically, user accounts used for spamming will be deleted, and any account that has never been accessed after six months will be deleted.
OK, so I've yet to actually replace this block with my latest tweet. However, Drupal 7 makes editing random blocks much easier, so I might just reinstate "random thoughts."