It's a bit off-topic, but since Uberlingen came up, here's some more information about TCAS in this incident from Burt Ruitenberg at the Manly Symposium (I hope I'm quoting accurately!):
In the conflict the Bashkyrian Tu 154's TCAS was the Master and the DHL's the Slave. When the Tu 154 descended in response to ATC instructions, its TCAS did not detect the fact that own-ship was non-compliant with the RA and therefore command a sense-reversal.
If, on the other hand, the DHL had been the Master it would have sensed non-compliance with the RA by the Tu 154 and would possibly have commanded a sense-reversal in the own-ship RA.