Despite the fact that Google has proven itself to be all but immune from threats posed by competing search engines, hope springs eternal. Within the past couple weeks alone, two new challengers have emerged, accompanied by much fanfare in the business press.

Microsoft takes yet another swipe at Google with its new Bing search engine. Based on an earlier one called “Kumo,” some industry observers — though not all — believe it is a pretty good competitor. Reviewers are particularly pleased with the presentation of refined versions of search queries. Bing also features a rollover display of each link’s content, allowing you to see how useful it will be before clicking through to the site.

The search engine also appears to index more recent “breaking news” items, whereas with Google, those results are not shown unless you click through to Google News — an extra step.

The big question is whether Bing will be able to wean web users away from their habit of searching on Google as their default choice. Certainly, Microsoft is putting some serious promotional dollars behind the launch — upwards of $100 million according to Advertising Age magazine. But based on the tea leaves, a wholesale change in search behavior seems unlikely. Search habits aren’t going to change dramatically unless there is a dramatic improvement in the effectiveness and speed of search activity. Fom what we see of Bing so far, we’re talking about improvements nibbling around on the margin rather than big sweeping change.

But “big sweeping change” just might be the recipe for Wolfram/Alpha, the other new entrant in the search engine sweepstakes. That’s because W/A isn’t actually a search engine in the classsic sense. Instead, its developers refer to it as a “computational knowledge engine” that uses complex algorithms to search databases to come up with answers to questions, rather than presenting a list of sources where the answer might be found. It can report some really cool factual results just based on the user typing in, for example, a date range, several city names, or an animal species.

The key difference between Wolfram/Alpha and Google is that W/A does not index web pages. Instead, it draws answers from a wide range of information-packed databases. So if you want to know the number and magnitude of hurricanes hitting North America in the past 15 years, you’ll get a specific answer rather than being presented with a series of web links wherein you might find the answer to be hiding.

Some observers see the potential for W/A and Google to team up rather than compete against one another. After all, what they do isn’t directly competitive, but in more respects complementary. And in an interesting twist, it turns out that Stephen Wolfram, the ~50-year-old computer scientist and developer who created the software platform upon which W/A is based (called “Mathematica”), once supervised a summer intern by the name of Sergey Brin — who would go on to develop Google with partner Larry Page.

Sergey and Stephen teaming up once again would be quite the coincidence … or would it really?