In Silicon Valley, crypto and the metaverse are out. That much became clear Monday night at the San Francisco Exploratorium, where Stability AI, the start-up behind the popular Stable Diffusion image-generating algorithm, gave a party that felt a lot like a return to prepandemic exuberance. The event -- which lured tech luminaries including the Google co-founder Sergey Brin, the AngelList founder Naval Ravikant and the venture capitalist Ron Conway out of their Zoom rooms -- was billed as a launch party for Stability AI and a celebration of the company's recent $101 million fund-raising round, which reportedly valued the company at $1 billion. But it doubled as a coming-out bash for the entire field of generative A.I. -- the wonky umbrella term for A.I. that doesn't just analyze existing data but creates new text, images, videos, code snippets and more. It's been a banner year, in particular, for generative A.I. apps that turn text prompts into images -- which, unlike NFTs or virtual reality metaverses, actually have the numbers to justify the hype they've received.