Just wondering if they have a bigger purpose. They are labelled according to the finger corresponding to each hand. It seemed like awhile back that (when Tobito dropped his in the rocks, formerly Sasori's) it was an important object. Even Orochimaru jacked his from the organisation.
There are three possibilities about the purpose of the rings (and how we will find out about it):
1) The rings are just aesthetic, like membership rings. If you have the correct ring worn on the correct finger, it's like a secret handshake that you are who you claim to be. In this case, they aren't important enough to mention again and we probably won't hear anything about them again.
2) It's something of use to Akatsuki, but is not super-important. For instance, they could be some kind of tool for Tobi to track down and find different members instantly, or a way for Pain to communicate with people using his hologram technique, or something like that. In this case, they might be mentioned in passing again, especially if Sasuke/Orochimaru revisit his laboratory and Sasuke sees it.
3) It's something very important for the operation of Akatsuki. In that case, we'll probably hear about them again in some kind of important story exposition or flashback from Madara or Obito.