Google's logo shifts this week – a swirl of balls, then a grey emblem that colours as you type – are something more mysterious than the usual doodle fun

After teasing millions on Tuesday by turning its logo into a swirl of balls that would avoid their mouse, Google on Wednesday seemed to go the other way - offering a plain grey logo which only changes colour to the normal blue, red, yellow, blue, green and red once the user starts typing.

Experienced Google-watchers believe that the change of logo – and of the "favicon" which appears in the address bar where the web address appears from a "G" to a tiny globe when viewed with Google's Chrome browser (though not others) – points towards changes that the search giant is due to announce in San Francisco later.

Among the expected announcements are more search results per page, "live streaming" results which will update as people type, and changes which may make it harder for people to fool its indexing system and push undeserving pages higher.

On Tuesday Google was evasive – rather like its logo – about the purpose of the "bubbles" version, saying only that it is "fast, fun and interactive, just the way we think search should be."

The "Grey Wednesday" logo is also interactive, which hints that Google is going to change the way it organises its search results. It has already experimented with self-updating results, which change the order of results as people type their search query, using a technology called Ajax which is more commonly seen on its Google Maps page: there, it dynamically updates the page as the map is moved around or the user zooms in and out.

The search results pages already incorporate Ajax technology in the left-hand column, where you can choose form results including "Everything", "News" and "More" - the latter offering an Ajax-style dynamic update when clicked.

As "A Googler" suggested on Twitter, the "boisterous" doodle of Tuesday might indicate that it's "excited about the week ahead".

The announcement at the Museum of Modern Art (MOMA) in San Francisco will include high-level speakers including Marissa Mayer, the Vice President of Search Products & User Experience, the Director of Product Management Johanna Wrigh, the "Distinguished Engineer" Ben Gomes, and Google Senior Staff Software Engineer Othar Hansson.

Mayer in particular has been outspoken about Google's intention to push real-time search: in an interview with The Guardian last year she noted:

""We think the real-time search is incredibly important and the real-time data that's coming online can be super-useful in terms of us finding out something like, you know, is this conference today any good? Is it warmer in San Francisco than it is in Silicon Valley? You can actually look at tweets and see those sorts of patterns, so there's a lot of useful information about real time and your actions that we think ultimately will reinvent search.""

However, the use of Ajax for Google results will be limited to modern browsers; it won't work older browsers such as Microsoft's Internet Explorer 6, which despite being a decade old is still widely used in corporations and organisations, including the National Health Service. Users of Internet Explorer 6 were unable to see the animated Google of Tuesday, or today's "colouring" logo.

That means though that people who use Google on newer browsers - including more recent versions of Internet Explorer, the Firefox browser, Google's Chrome and Apple's Safari - at home may be disappointed when they get different results at work. That may work in Google's favour as it tries to push its Chrome browser into greater visibility with organisations.

(Deleted reference to favicon: in Chrome the globe symbol indicates a link on the web, while the favicon is shown in the tab. Thanks to Brian Butterworth for pointing this out.