Deschanel, 32, who split from husband Ben Gibbard earlier this year after two years of marriage, was seen kissing Linden yesterday in Los Angeles, reported Us magazine.
The pair were first linked together in June after they appeared "inseparable, holding hands and hooking their arms together" at a "Magic Mike" after-party.
"Jamie's a really nice guy. He's funny, and a little geeky... He's into her!," a source said.
The brunette beauty had recently said that she likes intelligent men who make her laugh.
"I think intelligence and humour are probably the most attractive traits in a guy," she had said.