Seems like I recently read about using ceramic media in a case vibrator or tumbler - maybe Hand Loader or Rifle Magazines about November or so. Don't do black powder myself but the ceramic media title sure caught my eye. Seems like the author loved the new system.
It does seem to do a good job. You need a tumbler that can handle wet media to use this stuff, and the size of the ceramic media might make it work best in large bore, and/or straight cases.
I just put my cases into a jug of soapy water after shooting black powder. Shake it up really well, to get rid of the bulk of the fouling. Give the inside of the case a quick scrub with a small brush with more soapy water. It helps if you run them through a universal decapper before cleaning starts, so that the primer pockets get a little cleaner, too.
When the scrubbing is done, rinse them in hot water, and let most of the water evaporate off. Then, I throw them into the case tumbler, mainly to finish drying them. This method works to preserve your case and prevent corrosion, but it won't stop the brass from getting stained. The ceramic media polishes the stain off, so the cases look nicer. You're still supposed to rinse the cases before using the ceramic stuff, and you have to use a cleaning additive with it.
With the cost of getting a wet/dry tumbler, media, and cleaning solution, I'd be pretty close to the cost of a new gun, so my brass will stay dingy looking.
I have tried a quick dip in vinegar, and it cleans stained brass very quickly. As with the ceramic media, you're really removing a little bit of the outer layer from your brass, and the stain goes with it. It takes less than one minute to shine up brass in vinegar, and I wouldn't leave it any longer than 30-40 seconds. Rinse very well afterwards, dry the cases in front of a fan (I don't like putting mine in the oven), and voila, shiny cases.