The Apple rumour mill is now running at full tilt as would be expected during the few days before Macworld. While Everything Apple doesn't have inside information as to what exactly will be released, as I've mentioned before I do expect to see a new 13" Intel PowerBook to be announced during Steve Jobs' Macworld keynote on Tuesday:
13" 16:10 widescreen 1280x800 (or possibly 13" 1280x780)
Single-core 1.66 GHz Yonah Core Solo with 2 MB L2
ATI Mobility Radeon X1300 128 MB PCIe DVI-out
512 MB DDR2 built-in, upgradable up to 2.5 GB (PC4200)
Bluetooth 2.0 and Airport Extreme (possibly with 802.11a)
8X SuperDrive (No Blu-Ray or HD-DVD)
80 GB 5400 rpm hard drive (7200 rpm option)
Possible integrated iSight
Possible backlit keyboard
I am predicting that such a machine would use the 1.66 GHz Core Solo chip for a few reasons. First, one might expect that Apple would keep the 15" and 17" G4 PowerBooks around for a few months for those who require PowerPC support for certain applications. If Apple doesn't offer Intel-ified versions of those as well, then it means that a 13" Intel Core Solo machine would not have a faster clock speed than the 15" and 17" G4s. I realize that performance-wise it would be faster in most things, but it would still be OK in terms of marketing. Second, it's much easier to put a Core Solo chip in a 13" laptop than it would be for a Core Duo chip while still maintaining reasonable battery life and weight.
Built-in Airport Extreme (802.11b & 802.11g) support in the machine would be a no-brainer, but it's possible that Apple would add 802.11a support if they chose to leverage Intel's Centrino technology, since certain versions of it already support 802.11a. I would not expect support for 802.11n (which is much faster) until the second half of this year.
The Mobility Radeon X1300 was only announced a few days ago, but this GPU is expected to be shipping relatively soon. This GPU offers H.264 acceleration, something that would benefit both Apple's current H.264 push in QuickTime as well as future Blu-ray playback support. In addition, the most most recent mobile nVidia GPUs now also offer H.264 acceleration with PureVideo, so Apple could use an nVidia GPU instead of an ATI one if desired (and if the power utilization was sufficiently low). However, whether it's ATI or nVidia, it's possible that these GPUs that support H.264 acceleration may not be incorporated into Mac laptops until well after Macworld, when they are shipping with Blu-ray drives and the video drivers to support H.264 acceleration are mature. If that is the case, then Apple may choose to use something more along the lines of the Mobility Radeon X300 for Tuesday's 13" PowerBook.