as far as I know, only with new dbSNP releases submited SNPs (ie ss) are converted into reference SNPs (ie rs), and at that point all dbSNP files are updated and released. it is my honest belief that only with a new dbSNP release dbSNP files are modified, as this is what would make sense, but since I'm not in the dbSNP team I can't be completely sure about it.

the fastest way I know of finding out what's been going on at dbSNP is by looking at their build history, although it won't be the "immediate" tracking system you are expecting. I guess the only think you can do when changing from one build to other is to check the date and size of the dbSNP released file you're interested in.