I have written a utility that can read ITM trace data using a ST-Link V2. This functionality would be useful to have in st-util if possible. The only problem is when it detects a packet with length 0xF8xx, which I assume is an error code - possibly overrun. It recovers, but loses some of the data. Other than that, I have had it running for a few hours capturing data from an STM32F107Z.
See http://obe1line.github.com/stlink-trace/ for further details.
Somebody has enhanced your stlink-trace: https://github.com/avrhack/stlink-trace