Winehouse loves Soul music of the '60s and '70s, and it's likely that this song was inspired by the Billy Paul classic "Me And Mrs. Jones," which is about a couple who are cheating on their partners. In this song, Mr. Jones would be the man she is having an affair with, and she's clearly not pleased with him.
This is possibly the first song to name-check both Slick Rick and Sammy Davis, Jr. Slick Rick is a rapper who was popular in the '80s, and Sammy Davis Jr. was a legendary entertainer and part of Frank Sinatra's "Rat Pack." He was, as Winehouse sings, a black Jew.
The titular Mr. Jones is New York rapper Nas (real name Nasir Jones), who became good friends with Winehouse after being name checked. He told XXL in 2011: "I don't really remember if [producer] Salaam [Remi], who was really close to her, who introduced us, if he told me about it or not. But I heard a lot about it before I even heard the song."
Sadie from Atlanta, GaThis is about Amy's anger at a friend who either didn't get her tickets to Nas' concert or that she doesn't want coming with her to his gig. This person in the past has made her miss the Slick Rick ("Ruler") gig but she's saying pretty much she'll be damned if he makes her miss Nas (Mr. Jones= Nasir Jones). Nas played at Brixton in 2005.
Tiffany from Little Rock, ArThis is one of Amy's funnier soul tunes, where the singer downgrades her duplicitous lover (Blake Fielder-Civil, her current husband) saying "you ain't worth guest list" and "nowadays you don't mean d!ck to me" while admitting she's not much better because it's "me and Mr. Jones", meaning that she's still the other woman, she still loves him and "wonders about the things he does" and they're still having an affair.
Don from San Antonio, TxC'mon people, quit sitting on your hands...this page is BLANK!! According to wikipedia or something, "Mr. Destiny 9 & 14" is a reference to that dude NAS, who shares the same birthday as our heroine (no pun intended, seriously), and Destiny is his kid's name. She's been singing "Ray-Ray" instead of "Sammy", and clues point to a Ray Charles reference. The only thing I cannot understand about Amy is her respect for rap & hip hop. Lemme quote Henry Rollins on this situation: "The 50 year old female jazz singer sits on a bench waiting for the bus while the man with no talent drives by in a BMW 540iiiiiiiEEEEE!! (laughs) KEEP IT REAL MAN!!!"