Now most common in chatgroups -- previously observed at the village well, later the parish pump : a group enjoying a good old communal moan about anything and everything.
'I've given up that chatline -- it's now just a whingefest about everything that's wrong with urban life...'
'I left the dinner-party when it developed into a whingefest about the government...'
'That bitch is a one-woman whingefest -- it makes me tired just listening to her endless moans...