I noticed a new blue dot in front of some review queues. What does it mean?
As in many cases on Stack Exchange, you can hover over things and get more information about them:
Yaakov Ellis says it will go away in 60 days; if you want it to go away earlier, all you have to do is perform a review in that queue, or skip an item. (It's not enough to just dismiss the guidance popup.)
When they are really new queues they are so new that they've never been used.
The blue dot makes more sense in that case, though despite being used on some sites they are still "new" to some users; though the notification of purported newness is only retained for two months.
Here are a couple of unused queues:
This is what the HTML reveals:
<div class="s-activity-indicator flex--item mt6" title="The First questions queue is new"> <div class="v-visible-sr"></div> </div> … <div class="s-activity-indicator flex--item mt6" title="The First answers queue is new"> <div class="v-visible-sr"></div> </div>
These appear to be indicators that have a tooltip which simply says that these two queues are new.
Related announcment: Review queue workflows - Final release.