As for me 4340s things that work are:
1) CPU Speed Stepping - for core i5 2450m second generation
2) SATA controller
3) USB 2.0
4) Graphics - i have intel HD3000 with 2nd generation core CPU.
5) Ethernet - with Mac2Lnx driver for Realtek. But i don't
6) DVD-RW - reads natively, but don't verify write.
7) card reader with 3-d party drviers provided from installer
8) HDMI video + sound
Partially worked:
1) web-camera - worked in skype, but not with native osx apk's. Tested Photobooth, Facetime - not worked.
2) USB 3.0 - can't see USB HDD/Flash, but worked with USB receiver for wireless mouse. Don't work with USB wifi adaptor.
3) Bluetooth - straight after fresh installation 10.8 it was, but after 10.8.1 can't see any devices.
4) Ethernet - with Mac2Lnx driver for Realtek. Don't know
5) AppleHDA - generally worked, but volume is not so high, external mic is not working. Position is not
6) Brightness control - with DSDT fixes, worked fully only after sleep and get up. Generally is works.
7) Wireless button worked for bluetooth but after 20-30 sec you can see bluetooth device disappeared from osx. After push again and wait for 20-30 sec it appears.
Don't work
Wifi module AR9485 - AR5B225 (combo Bluetooth 4.0 + Wifi-n upto 150Mbit/sec) - need to be replaced