What is this 48-pin laptop hard drive connector?

This is a PowerBook special and is not a PATA/IDE connector at all. It's a SCSI connector! Apparently a very custom SCSI connector that isn't really supported elsewhere, though it appears to be electrically (if not mechanically) compatible with standard SCSI-2 so an adapter is possible.

Some more info at: http://vintagemacmuseum.com/reading-powerbook-2-5-scsi-hard-drives/

There's some discussion over at https://68kmla.org/forums/index.php?/topic/31589-40p-scsi-to-50p-scsi/

There are also devices available that emulate such a drive (using a SD card as backing storage). Note the pinout in the photo matches your drive.

According to EveryMac the laptop you mentioned uses a SCSI connector for its internal drive connections.

Standard Hard Drive: 80 MB, 120 MB* Int. HD Interface: SCSI

Details: *By default, this model is equipped with an 80 MB or 120 MB internal SCSI hard drive.

^{Emphasis mine.}

The 8 pins to the left of your image will probably be used to indicate the SCSI ID of the drive, normally using jumpers. The original version of SCSI could daisy-chain up to 8 devices.