MacNN has exclusive shots of yet another banner from Apple's worldwide developer conference that makes reference to Microsoft's yet unreleased operating system. Taking yet another jab at Microsoft using its annual developer conference at the Moscone Center West in San Francisco, a newly photographed banner reads 'Hasta la vista, Vista." Apple, expected to debut its next-generation operating system, Mac OS X 10.5 Leapard, is trying to out-duel Microsoft, whose next-generation Windows operating system has been delayed many times. Another banner (not photographed) says 'Redmond has a cat problem', according to a MacNN reporter. On Sunday, we noted the "Vista 2.0" banner photographed earlier in the weekend. As usualy, we expect the online Apple Store to be taken off-line temporarily while the company updates/adds new products. MacNN will offer live coverage of the event at live.macnn.com.