For those who miss the days of Apple's sub-notebooks such as the PowerBook Duo and the PowerBook 2400, good news may be around the corner. An article over on AppleInsider both explains Apple's history with the its sub-notebooks as well as describes a MacBook sub-notebook which sources close to the project say is ahead of its Apple Worldwide Developer's Conference ship date this June.

The laptop, while noted as lacking an optical drive, is expected to include most of the features present on the current MacBook while introducing a NAND-flash based memory system. The solid-state memory, which uses no moving parts, is anticipated to improve power efficiency and help provide near-instantaneous boot times, although this has yet to be frozen into the final design build according to sources.

Even if some don't consider a sub-notebook to be critical to Apple's lineup, the effort would help Apple in its Japanese markets, where Mac sales declined about 14% as of the company's 2007 first fiscal quarter report.

"The market in Japan is among the weakest in the world," Apple's second in command, Tim Cook, told analysts during a recent company conference call. "However, having said that, we're not pleased with our performance there and we've got a number of activities underway to attempt to improve them."

The company, which launched a localized "Get a Mac" ad blitz, seems to be working to make itself known to the nation and the region in general, a bleeding-edge sub-notebook being the next logical step for a market it wants back.

If you have any thoughts or opinions about an Apple sub-notebook, let us know.