Then Skype got bought by eBay shortly thereafter for gobs of money, in the somewhat blind hope that synergies would develop between eBay, PayPal, and Skype. Never quite panned out that way.

Btw, although I've seen little difference between HipChat and Slack in my day-to-day, the switch from Skype to HipChat was a profound improvement. Messages sent on Skype could and would frequently vanish into the ether, and/or arrive in the conversation thread way out of order. Imagine troubleshooting production issues under those conditions!...