Der Spiegel stands by its story:

Obama is pleased, but McCain certainly is not. In an interview with SPIEGEL, Iraqi Prime Minister al-Maliki expressed support for Obama's troop withdrawal plans. Despite a half-hearted retraction, the comments have stirred up the US presidential campaign. SPIEGEL stands by its version of the conversation.

As well they should. They had an on-the-record interview in which Maliki's remarks were not at all ambiguous and during which time he repeatedly returned to the subject of thinking that Obama's proposals are the right framework within which to proceed. Against that there's a non-denial denial, in another person's name, issued by CENTCOM. Considering that Maliki in effect lives and works inside a CENTCOM controlled military installation, that's some exceedingly weak tea he served up.