Ubuntu
last <username>
AIX
lsuser -a time_last_login "ALL"
will show the last login time in seconds for all users... seconds after 1/1/1970
To make any sense of the long string of digits you need to convert it...
convert-epoch-seconds.php
(which uses php echo date('r',number);)
To copy and paste it enable quick-edit mode (cmd properties) and the highlight (it will automatically copy)
You must be root to use this (a normal user will get an Invalid Attribute Error).
[p630n02][/]> lsuser user3