The Tribune reports today that the Cubs have indeed been looking at Arizona's Tony Clark:
After a big year in 2005, when he hit 30 HR in only 349 AB, Clark (who turns 34 next month) is hitting .194 so far this year with only 1 HR. He's not starting most games, as D'backs rookie Conor Jackson won the starting job. Clark does have seven walks in 43 plate appearances and has a .341 OBA.
I suppose it depends on what you'd have to give the Diamondbacks for Clark, who lives in the Phoenix area and doesn't really want to leave, and further, would be redundant (another tall right-handed-hitting 1B) once Derrek Lee comes back.
Also, my sources say that there has been no discussion of acquiring Carlos Pena if and when the Yankees let him go (he must either be called up or waived by tomorrow).