There really isn't enough information in this short article for me to decide if this is an unconstitutional state endorsement of religion or not.
MADISON - The Wisconsin-based Freedom From Religion Foundation is warning a middle school in southern Ohio about a Jesus portrait hanging in its halls.
The local school district’s superintendent of schools says he won’t remove the picture with an order from the school board or a judge. He says the display comes from a student’s initiative, which makes its permissible for display.
The question is thus: Is this a permanent, or temporary display? If its a temporary display of student artwork, and displayed in conjunction with other student artwork, I'd contend that the display meets Constitutional muster. If, however, its a permanent display, then it matters not if it was done by a student, it falls into the same category as the Rhode Island "prayer banner."
UPDATE 1/8/2013: Hemant Mehta has more detail. Its clearly unconstitutional.