Meta CEO Mark Zuckerberg posted his first message on his company's 'Threads' app, which is set to rival Elon Musk's Twitter. "Let's do this. Welcome to Threads," Zuckerberg posted on Threads ahead of its official release on July 6. Other accounts including those of Instagram head Adam Mosseri, entrepreneur Gary Vaynerchuk and brands like Netflix also went live on Threads.