The FAQ at Updated 16 July: Frequently Asked Questions about Raspberry Pi says
Q. What is the status on compliance testing for the Raspberry Pi?
A. The Raspberry Pi computer has now passed all of the necessary compliance checks and we will shortly start shipping to our global customers. For the Raspberry Pi, testing has been completed on CE, FCC, C-tick and REACH. We will send comprehensive safety information with the product that will cover Warnings, Instructions for Safe Use and Compliance Information. If you are interested in learning more about electronics legislation, please consult our Legislation area on the community.
One might reasonably assume that passing "all of the necessary compliance checks" would include FCC Class B (residential) tests, since the device is being sold primarily to residential customers, but the Safety Data Sheet at Raspberry Pi Safety Data Sheet says:
FEDERAL COMMUNICATIONS COMMISSION (FCC) EMISSIONS COMPLIANCE STATEMENT
- This equipment has been tested and complies with the limits for a Class A digital device, pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment.
- This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) this device might not cause harmful interference, and (2) this device must accept any interference received, including interference that might cause undesired operation.
Warning: Operation of this equipment in a residential area is likely to cause harmful interference, in which case the user will be required to correct the interference at their own expense.
If in fact the device does not pass FCC Class B testing, and "in a residential area is likely to cause harmful interference", then is it be legal to sell in the US to residential customers?