[Update, 10 a.m.: The official name is "Google Instant," and the company did, in fact, formally unveil the feature in San Francisco this morning. Here's the official 'about' page. It's already rolling out, and many of you may be seeing it on Google now.]

Google is holding an event in San Francisco later this morning to share its "latest technological innovation" -- but it looks like some people using the search site may be already getting a preview.

Various users report seeing a new Google "streaming" feature that displays (and changes) search results dynamically as people type in the search box, without requiring them to click the search button. Here's a video, captured by WebSonic.nl, via Search Engine Land.

The rise of Microsoft's Bing search engine has put new pressure on Google to make continued improvements in its user experience and underlying technology. Bing recently completed its integration with Yahoo in the U.S., boosting its market share to about 30 percent. That's still less than half of Google's market share, but Microsoft says it will better position Bing to challenge the search giant.

Check back for details of Google's news later this morning. One of my big questions: How will "streaming" search affect efforts by comScore and other market research firms to track the number of queries made via Google?