On the left side of my Lenovo T400, before the floppy disk drive, there are two plastic little bars. When pushing either of them, it can pop out; if push it again, it can go back inside.
I was wondering what these bars are used for?
I don't know the laptop, but is sounds like the blanks for a PC-Card (PCMCIA) slot. These cards were typically used for modems or other I/O expansion cards.