By Kasper Jade

Published: 03:50 PM EST

A forthcoming update to Apple Inc.'s 13-inch line of consumer MacBooks won't deliver much in terms of new features, AppleInsider has learned. Meanwhile, the dimensions of the company's ultra portable sub-notebook initiative are taking shape.

MacBook update

People familiar with the Mac maker's portable plans tell AppleInsider the Cupertino-based firm is looking to absorb a bit more from its initial 13-inch MacBook design.

Unlike an upcoming revision to its professional 15-inch MacBook Pros, the next version of Apple's consumer MacBooks is unlikely to benefit from architectural enhancements recently presented as part of Intel Corp.'s "Santa Rosa" notebook platform.

Similarly, the 13-inch notebooks won't reap the benefits of an LED-backlit display until a successive revision later in the year.

As it stands, the MacBook remains the most rigorously-redesigned Mac system to break free from Apple's industrial design labs in recent years -- an accolade it will soon surrender to a pair of radically restructured 20- and 24-inch iMacs.

MacBook Pro update

For the time being, Apple will reportedly focus on boosting the grade of its professional MacBook Pro line which, unlike the MacBook, is expected to draw an enhanced set of features from Santa Rosa.

These should include faster front-side bus speeds of 800MHz, and second-generation Core 2 Duo mobile processors that scale up to 2.4GHz.

As reported by AppleInsider, a new 15-inch MacBook Pro model will also signify the first Mac to trade in its cathode fluorescent-backlit display for one that uses LED backlighting.

MacBook ultra-portable

At the same time, Apple continues to pound away on an ultra-thin portable designed to capture a slice of the growing sub-notebook market and boost sales in Japan.

In what's sure to be a warmly received move, people familiar with initiative tell AppleInsider that the Mac maker plans to go easy on our eyesight and is building the model around stunning, ultra-thin, 13-inch LED backlit display.

That's right -- it appears those recent Apple orders for 13-inch LED backlit panels are destined for the firm's ultra-portable initiative and not its impending 13-inch MacBook update.

Combining this latest tidbit with information presented in previous AppleInsider reports, here's a summary of what we know and don't know about the next-gen Apple sub-notebook:

What we know:

• 13-inch ultra-thin, LED-back lit display
• No optical disc drive
• On-board NAND flash for faster application launching and boot times
• Built-in iSight webcam
• Thinner and lighter than existing MacBook offerings
• AirPort Extreme 802.11n enabled
• MagSafe power adapter
• Target launch late '07, early '08

What we don't know:

• Precise Intel architecture (but appears to be Santa Rosa-based)
• Target price point
• RAM and HDD storage capacity and expandability
• I/O port breakdown
• Operating system software (appears to be Leopard)
• Expected battery life
• Enclosure makeup

Additional reading (backstories):
Next-gen MacBook Pro to shine brighter
Apple to re-enter the sub-notebook market
Apple's next-generation iMacs to add a touch of grace
Resetting the timeline for Apple's ultra-portable initiative
Steve Jobs confirms first Macs with LED backlighting due this year
Apple delays Leopard release until October
Apple moves to certify LED-backlit panels for 13-inch MacBooks
Intel rolls out Santa Rosa notebook platform