Samsung posted the full specs of the upcoming SM-348B combo drive. It supports 48X writing, 24X re-writing, 48X reading (CD) and 16X reading (DVD)...

Key feature

COMBO Drive combines CD-RW and DVD-ROM Drives into one mechanism
Buffer Under Free Technology
High Capacity Buffer Memory:8MB
Reduces noise and vibration with DVA(Dynamic Vibration Absorber)
Reads DVD-R,DVD-RW Discs

Specifications
Write on CD-Record 48X ( 7,200 KB/sec)
Write on CD-Rewrite 24X ( 3,600KB/sec)
Read CD Titles 48X (7,200KB/sec)
Read DVD 16X (21,600KB/sec)
Burst Transfer Rate
PIO Mode 4 (16.6 MB/sec)
DMA Mode 2 (16.6 MB/sec)
Ultra DMA (33.3 MB/sec)
Average Access Time: CD: 110ms, DVD: 130ms
Supported Disc DVD-R/RW,DVD-ROM.DVD-Video, CD-R,CD-RW,CD-DA, CD-ROM/XA, Video-CD, CD-I, Photo CD, Extra CD, CD-Text
Recording Capacity
CD-RW Disc 700/650MB(type 80/74)
CD-R disc 800/700/650/550MB (Type 90/80/74/63)
Interface EIDE/ATAPI
Buffer Memory 8MB
Flash Memory 1MB
Drive Mounting Horizontal/Vertical
Writing Method
DAO (Disc At Once)
TAO (Track At Once)
SAO (Session At Once)
Multisession
Packet Writing (Variable, Fixed Packet)
Physical Specification
Dimensions (WxHxD mm) : 148.2 x 42 x 184
Weight (kg) : 0.77