Specifically, Google announced today that developers can not only build extensions, but also upload them into Google’s gallery showcasing Chrome extensions. That way, “developers have time to publish their extensions ahead of [Google's] full launch.” The post doesn’t include any specifics on when that full launch will come, but it sounds pretty close.
Google also says developers don’t need the company’s approval to upload Chrome extensions, unless they include “NPAPI content” or “affect ‘file://’ URLs” — in those cases, the extensions have greater access to your computer and must be screened for security risks.
This may be significant news for developers, but personally, I’m underwhelmed — as much as Mozilla likes to tout the number of extensions for Firefox, I tend to avoid them since they slow down the browser. In fact, Google Gears is the only extension I use, and it’s already included in Chrome.