Yes, this also applies to the computer users on the other side of any 'conversation'. Anywhere such transmissions are unprotected they can be eavesdropped upon, and all participants are vulnerable to this including those who are 'hard wired' to the internet. The eavesdropper only needs to listen and record at the weakest link.
For the radio specs involved check out
this Wikipedia link, but realize that to listen in on WiFi conversations you essentially already have all the necessary hardware and software with a WiFi enabled laptop, and only need an access password, if that...
