Is the avian bird flu a foodborne illness via chickens?

No: It is transmitted through contamination of air. Transmission from birds to humans requires close contact with infected birds. Properly cooked chicken meat does not transmit bird flu.

Not really: Bird flu is transmitted after contact with infected surfaces - so, if one has contact with infected surfaces then bird flu can be contracted. Having said that - bird flu is exceedingly rare (and hasn't been documented in the western hemisphere at all) and thus you are much more likely to get salmonella or campylobacter (usually causing food poisoning/diarrhea) from uncooked chicken more than flu.