Web search is evolving to become both more personalized and specialized, said a panel of well-known search pundits at the Search Engine Strategies Conference and Expo in New York Tuesday.

While the number of so-called vertical search engines, which allow users to search within a specific area of interest, is increasing, the panelists did not think these search engines would pose a large competitive threat to traditional Web search providers.

David Vise, author of The Google Story, said vertical search would affect traditional search in the same way cable has impacted network television.

"Cable TV's done OK taking some share from the networks, but the networks still exist. I see something similar developing over time in search," said Vise.

"I don't agree that vertical search will take away share from the major search engines," said Jeremy Zawodny, with Yahoo Inc. "Vertical search provides specialized services for specialized needs. If I'm looking for a rental car, I don't turn to the Web search for that."

Matt Cutts, senior software engineer for Google, pointed out that it's fairly easy for traditional search companies to spin out vertical search sites if they want to because they already have the technical know-how.

But, the panelists didn't discount the power of smaller, specialized search tools.

"Small companies can take on the big boys," said Robert Scoble, a technical evangelist for Microsoft. As an example, he pointed to Technorati.

Regardless, users are expanding the number of search engines they use, said Zia Wigder, vice president and research director for JupiterResearch.

"The number of search engines people use grew from 2.5 in 2003 to 3.2 in 2005, and we expect to see those numbers increase in the future" said Wigder. The retail industry is one example of a market in which vertical search has already caught on, Wigder said.

Another trend the panelists touched on is the increase of "social search" services, such as Del.icio.us.com (acquired by Yahoo in 2005), that allow users to personalize search by doing things like tagging information with keywords and then sharing that information with other groups.

"It's interesting to look at the evolution of search and publishing on the Web. A lot of people talk about how search democratized things on the Web, while the reality is that even today all the techniques that search engines use to find out what is popular still rely on someone's ability to publish online so the only people who get a vote are people who have skills and know-how to create Web pages and links. Services like Delicious really lower the barrier to a much larger number of people contributing to what's interesting online," said Zawodny. "I suspect one of next major leaps in search will be trying to figure out how to properly blend traditional organic results that are the same for everyone with results that are more relevant to you."

"There is a ton of opportunity there, the question is how ready is it for the mainstream," said Cutts.

Panelists also touched on several challenges facing the search engine industry, including the ever-popular spam.

"In Web spam, over the next few months the big watchword is international spam fighting," said Cutts. Google is "ramping up" its spam-fighting efforts beyond the English language, he said.

The difficulty of distinguishing relevant links from irrelevant links is also an ongoing challenge, but one that cannot be solved with technology alone, said the panelists. End users can also lend a hand in this effort by using more advanced search techniques.

"The search terms are so small that with a sizeable percentage of searches any human can say there are a lot of ways I can interpret that," said Zawodny.

Video search also still poses technical obstacles, said the panelists.

"I'm skeptic about video because anytime I've ever tried to watch video it hasn't worked...it's only just now that stuff like that is starting to work," said Cutts.

"Video's interesting, but there are a lot of technical challenges still on the back end to improve video," said Zawodny. "I think the search consumption with video will be different than Web search, but no one has quite figured out what that will be yet."