I have this exact same problem now.

I had my calipers replaced on the front, about two weeks later the abs/brake lights came on with the VSC TRAC and VCS OFF, and then the speedometer stopped working shortly thereafter.

Firestone did the brake job, and claims that this is all unrelated. It seems highly coincidental that this would be the case, but i guess stranger things have happened. The OP never followed up, so i'm curious what my options are here...

Firestone tried to replace the speed sensor and determined that wasn't the problem, and now they are sending me to the dealer. Could it be related to the caliper work that they did?