In reference to the patent: US6608366
Is US 6,608,366 B1 in the public domain?
No, US 6,608,366 B1 and the continuation patent US 7,183,630 B1 (from the same application) are not in the public domain. I double-checked the Public Pair records to verify. Both of these patents are enforceable until April 15, 2022.
Please also refer to a related question describing how to calculate patent expiration dates.