According to a report in Reuters:
The "Love Detector" service from mobile operator KTF uses technology that is supposed to analyze voice patterns to see if a lover is speaking honestly and with affection.
"We created this service because we thought people would want to know what others were feeling about them," said Ahn Hee-jung, a KTF official.
Users who speak by pointing their mobile phones at themselves for video conferences can see a "love meter" bar on the screen of their handset during a conversation.
They later receive an analysis of the conversation delivered through text message that breaks down the amount of affection, surprise, concentration and honesty of the other speaker.
The service costs subscribers a flat fee of 1,500 won ($1.59) a month for unlimited use or can be accessed at 300 won for each call, KTF said.
"The caller is paying the money, so the information is provided only to him or her," said Ahn.
So the next big thing would be "Thought Reader" to find out what the person was thinking when he was talking to you ;)