Even if Google said that the particles animation didn't celebrate a special event, it's probably the first time when Google uses doodles to build anticipation before launching a new feature. The doodle was fast, fun and interactive, just like the new search interface that shows results as you type a query.
Today, Google's homepage has a new doodle that shows a monochrome Google logo. When you start typing your query, Google brings back the color one letter at a time.
The doodle looks exactly like the new interface for Google Suggest:
It's now obvious that Google will launch "streaming search" today. Even Google's Twitter account confirms this: "Our doodle is dressing up in its brightest colors for something exciting coming very soon".