Does Bing have a challenger in Caffeine, Google's newest search engine tweak? According to the Official Google Webmaster Central Blog, a large team of Google engineers has been kept in virtual lockdown over the past few months, developing "next-generation architecture for Google's Web search." As you can see from the Web developer preview, the page looks pretty much the same, but allegedly there's now a supercharged engine under the hood.

My rock-star colleague Clint Boulton gives a deeper rundown from the Google side of things here.

Soon after the launch of Microsoft's Bing search engine on June 3, Google CEO Eric Schmidt said in an interview with Fox Business Network, "I don't think Bing's arrival has changed what we're doing." Nonetheless, other reports surfaced that a high-level team at Google was already dissecting Bing to find out what exactly made it tick.

If Caffeine is the result of that research, it doesn't really show -- the search times may vary by a few microseconds, but the results seem largely the same. As a simple test, I entered the search term "Microsoft Watch" into both search engines. This is what you get with Caffeine:

And here's what you get with Bing:

Both offer the same top result, while the links below that vary between Bing and Caffeine. One doesn't seem to have an upper hand over the other, although my ego is slightly bruised by Bing's failure to include my name in that little search bar on the left.

Here's what happens when you enter a more everyday search term. Because I'm currently plowing through the DVD set of "24," Season 7, I chose "Jack Bauer." Here's what you get with Caffeine:

And here's what Bing offers:

Here the multimedia results are a little different. Google's Caffeine variation seems to think that you'd like your Video and News results at midpage (weirdly enough, it doesn't offer Image results, something that the regular Google does just fine). Bing would prefer to hit you with the breaking News up top, and leave Image and Video results for the bottom of the page (not shown). I continue to not be mentioned in that little search bar on the left.

End result: Whatever Google's attempting, it doesn't seem to be a direct countermeasure to Bing so much as a more generalized tweaking. Over the past few months, analysts have described Bing's battle as an uphill one precisely because people have fallen into the habit of using Google, and are unlikely to shift over unless the latter breaks in some catastrophic way. Google may figure a performance adjustment may be all it needs to maintain its comfortable double-digit marketplace lead over Microsoft's upstart.

That upstart, however, has now grown to twice its original market share, thanks to the search and advertising deal inked between Microsoft and Yahoo on July 29. With Bing powering Yahoo's search engine in exchange for Yahoo becoming both companies' worldwide online sales force, Bing's share of the market jumps from 8.4 percent to nearly 30 percent, making it a more robust competitor to Google.

Whatever Caffeine ultimately represents for Bing, I get the sense that a far more interesting search-engine battle is just beginning. What do you think?