Panasonic has officially announced their 4x Blu-ray Disc writer, the LF-PB271JD. This new drive sports a Serial ATA interface and is capable of writing to both BD-R and BD-R DL media at 4x. Here's part of their press release, translated from Japanese:

The Panasonic marketing headquarters sells the Blu-ray Disc drive for the personal computer data from November 10th. The Blu-ray Disc format of BD-R, BD-RE and BD-ROM which the blue ray disk association standardizes is supported not only, the DVD-RAM disk (5 time speed) and the like DVD MULTI and the CD format were supported, wide compatibility high record playback efficiency was actualized. High picture quality treble quality of the hi-vision times which have started spreading quickly it is the Blu-ray Disc drive for the personal computer data which actualizes bulk data retention such as digital image.
The LF-PB271JD will be released to the Japanese market on November 10th. While Panasonic has announced a price, AV Watch expects the drive to cost about 55,000 Yen ($471US). More information, including a full list of specs, can be found here.