Thanks for all the responses!
I spoke with a TSA screener who said he sees emergency chutes often, and rarely has to open one. It's their policy however that if their alarm is triggered, it has to be unpacked.
It took about a month, but here is the response from the TSA from the same question submitted to their website:
"Thank you for your electronic message of March 31, 2010, to the
Transportation Security Administration (TSA) Contact Center concerning
traveling with two emergency parachutes. You would like assurance that
the parachutes will not be deployed or unpacked during the screening
process.
Parachutes presented at the screening checkpoint must undergo
additional screening beyond x-ray inspection. Parachutes routinely
will not be opened; however, if during the additional screening the
parachute alarms, it must be opened or it will not be allowed in the
sterile area.
We recommend that you contact the TSA Customer Service Manager at
your departure airport, prior to your flight, for further guidelines for
transporting parachutes. You may also want to contact the aircraft
operator and inform them of the items you will be transporting in case
they have additional requirements.
Thank you for your inquiry and I hope this information is helpful."