After months of incubation as a mere preview download, Yahoo Messenger for Vista is now a full-fledged…beta. No matter, let the feedback loop continue with this dark and gleaming desktop chat application that elevates certain aspects of the instant messaging experience while falling a step behind in others. The new look and feel is certainly impressive, and beloved avatar and emoticons take center stage alongside the tinted display. But the multiprotocol IM client Digsby is snapping up a loyal following, and its adoption of Facebook chat adds strength to strength. Is Yahoo’s effort strong enough to win back Vista defectors?