MacRumors.com

The Register posts a story about a small html reference on Apple's Powerbook site.

According to the news site, the following url reference appeared on Apple's Powerbook pages:

http://switch.atdmt.com/action/apple_g5_powerbook

The reference was in an IMG tag, speculated to be a counter for Apple's various individual web pages. The reference was changed to apple_g4_powerbook shortly after the publishing of the story.

Rumors have placed a G4 Powerbook upgrade in the coming days/weeks.

[Update] The requirements section of Apple's 17" Apple Studio Display page says in French

Configuration requise: L’Apple Studio Display nécessite un Power Mac G5 avec un connecteur ADC ou un PowerBook G5 avec un port DVI vers ADC Apple

Meaning: The Apple Studio Display requires a Power Mac G5 with an ADC or a PowerBook G5 with a DVI port and an Apple DVI to ADC Adapter.