

WhatsApp now shows when texts you sent have been read - xmpirate
https://www.whatsapp.com/faq/en/android/28000015

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This is similar to Blackberry's BBM service. Note that this doesn't apply to
text (aka SMS) messages, but only to WhatsApp messages sent via a data
connection.

EDIT: Yes, pretty much any IP-based messaging service has this capability.

