According to Appleinsider Apple has informed resellers to not expect any further shipments of the iMac G4, leading the way for an iMac G5 (Previously Rumored) and has delayed PowerMac G5 shipments to some resellers for weeks to come.
Additionally, Apple Cinema displays of both the 20" & 23" models are showing signs of dwindling inventory, leading to the release of new displays to coincide with the release of an updated PowerMac G5 at the World Wide Developers Conference beginning June 28th.
Metallic displays have also been previously rumored.
