Though he doesn't mean it in a bad way!
September was something of a rough month for Google, what with it having been hauled in front of the Senate Committee on the Judiciary Subcommittee on Antitrust, Competition Policy, and Consumer Rights to answer for accusations that they engage in anti-competitive business practices. Its dominance of the search engine world remains secure, for now, but if their responses to questions posted to them by that Senate Committee are any evidence, Google may be preparing for a post-Google rules everything around us world. Those responses have now been posted to Google Docs, revealing the position Google took in its own defense. In short: we are totally vulnerable, honest!
Google was represented at those hearings by Executive Chairman Eric Schmidt, who stated outright that "Google has many strong competitors and we sometimes fail to anticipate the competitive threat posed by new methods of accessing information". He specifically cited Apple's Siri app as a potential threat to Google's search engine dominance, calling it "a significant development—a voice-activated means of accessing answers through iPhones that demonstrates the innovations in search."
This comes in direct contradiction to statements he made in September, 2010 that Bing, not Apple or Facebook, was Google's biggest competitor. Acknowledging this, he said "My statement last September was clearly wrong... We compete against a broader array of companies than most people realize, including general search engines (Microsoft’s Bing, Yahoo!), specialized search engines (Kayak, Amazon, WebMD, eBay), social networks (Facebook, Twitter), commercial software companies (Apple, Microsoft), mobile apps, and even direct navigation. The Internet is incredibly competitive, and new forms of accessing information are being utilized every day."
Siri is of course a very cool app and Facebook will almost certainly defeat Google Plus. Taking into account that Apple's share of the home computer market remains dwarfed by PC (even accounting for insanely large iPad sales), it's likely that Google's market dominance is likely to continue for some time. It is obviously in Google's best interest to emphasize the strength or its competitors, real or not. A much better defense than, say, 'we're only on top because we already control the market' or 'switch to the new look'.