I also found the i7z utility for reporting CPU speed, apparently including Turbo Boost speed:
(You'll need to install libncurses5-dev from the repository before making this).
This tool seems to work great. Here is sample output:
It shows that the max CPU speed is 33x of 100 MHz, which should be 3.3 GHz. However, I still never see the speed crack 2.2 GHz under load.
Cpu speed from cpuinfo 2192.00Mhz
cpuinfo might be wrong if cpufreq is enabled. To guess correctly try estimating via tsc
Linux's inbuilt cpu_khz code emulated now
True Frequency (without accounting Turbo) 2192 MHz
CPU Multiplier 22x || Bus clock frequency (BCLK) 99.64 MHz
Socket  - [physical cores=4, logical cores=8, max online cores ever=4]
TURBO ENABLED on 4 Cores, Hyper Threading ON
True Frequency 2291.64 MHz (99.64 x )
Max TURBO Multiplier (if Enabled) with 1/2/3/4 Cores is 33x/32x/30x/30x
Current Frequency 2192.35 MHz (Max of below)
Core [core-id] :Actual Freq (Mult.) C0% Halt(C1)% C3 % C6 % Temp
Core 1 : 2192.07 (22.00x) 8.44 84.4 6.13 1 309
Core 2 : 2192.35 (22.00x) 1 98.7 1 0 308
Core 3 : 2191.95 (22.00x) 1.39 96 1.58 1 306
Core 4 : 2192.00 (22.00x) 100 0 0 0 311
C0 = Processor running without halting
C1 = Processor running with halts (States >C0 are power saver)
C3 = Cores running with PLL turned off and core cache turned off
C6 = Everything in C3 + core state saved to last level cache
Above values in table are in percentage over the last 1 sec
[core-id] refers to core-id number in /proc/cpuinfo
'Garbage Values' message printed when garbage values are read
Ctrl+C to exit
One other interesting quirk: I had disabled hyper-threading in the BIOS because I was seeing some undesirable behavior when running multiple compute jobs simultaneously (sometimes the jobs would get 50% of a CPU instead of 100%, even with 4 or fewer jobs running). With hyper-threading disabled all cores were always running 2.2 GHz and never throttling down with no load. With hyper-threading enabled, each core tends to run in the 800-1600 MHz range when not under load, and then with one compute job running all cores crank up to 2.2 GHz, even the ones not under load. Weird.
Still, I never see any more than 2.2 GHz on any one core.
Seems like maybe proper Sandy Bridge support is lacking in the 2.6.38-8 kernel?