Normally the HD DVD / Blu-ray discussion revolves around consumer video products, but we need to keep in mind that both formats are also used for data in PC applications. This is an area BD really shines, with its higher capacity. The new Panasonic drive can write a 25GB single-layer disc in 23 minutes, and a 50GB dual-layer disc in 43 minutes. Panasonic will release 4x 25GB BD-R media this month, with 4x 50GB media to follow in September.
LG also has a 4x BD-R burner, but it only handles single-layer 25GB media. LG is aiming for 6x speeds in their next generation of drive. Note that the ‘x’ multiplier is format specific – the base ’1x’ transfer rate for DVD is about 10Mbps. For HD DVD and BD it is 36Mbps. So 4x BD has transfer rates similar to what 14x DVD would be. We should see more 4x BD-R drives from other vendors soon. I believe HD DVD is still at 2x for the fastest drives.
From CDRInfo.com by way of Blu-ray.com