Some information about Intel's 4 series of chipsets has been published at Tweaktown. For premium and mainstream applications there's the P45 and on the lower-end there's the G43 and G45.
The G45 and G43 chipsets will be paired with the ICH10/R southbridge and will feature integrated DirectX 10 graphics. The chipsets will feature HDMI, DVI, DisplayPort and SDVO video at resolutions of up to 1080p.
Not all details are available yet but it seems one of the major differences between the G45 and G43 is that the latter one lacks hardware AC1 and H.264 decoding.
The G45 and G43 chipsets will be released in Q2 2008. In the same timeframe Intel will launch the P45 chipset but little is known about this chip.