Hoopla around Google Wave service, launched publicly in September, has brought resurgence to the idea of unified communications — a single platform that integrates voice, email, fax (really!), chat, and web conferencing. Long a dream of the telecommunications industry, unified communications is gaining some buzz among corporate tech teams as a possible tool for enhancing employee productivity.

As tech executives ponder their options, vendors of communications services are racing to grab share in the nascent market. But so far, it’s not online voice purveyor Skype or event Google (GOOG) that is making real waves in unified services — so far. Instead, the leader is a relatively unknown company: Citrix.

Citrix Online is the dark horse — some would say underdog — of the web conferencing space. (Citrix Systems was founded in 1989, acquired Expertcity in ’03 and renamed it Citrix Online, which oversees the company’s remote collaboration tools.) As Cisco (CSCO), Microsoft (MSFT), and IBM (IBM) fought for big Fortune 500 enterprise clients during the 2000s, Citrix focused on small to medium-sized businesses. From 2006 to 2007, Citrix’s revenue increased 50% and jumped more than 100% the following year to 101.4 million, according to Gartner data. And analysts expect the same growth this year.

The company delivered a product that had the right amount of features at the right price, says Roopam Jain, Frost and Sullivan’s principal analyst for collaboration.

“Citrix has been very aggressive around the SMB market,” Jain says. “Citrix has seen the fastest growth in this space; it’s brought meaningful market prices and hit what everyone wants — the sweet spot.”

Serving the small business sweet spot

Citrix is now hot on the heels of IBM and Microsoft — and if it continues to grow at the same rapid speed, it would be a surprise to no one if Citrix surpassed both these tech giants in market share. But compare Citrix’s 2008 101.4 million revenue to Cisco’s $551 million revenue figure, and Citrix still has a long way to go.

Timing is everything. For years, small-to-medium businesses were notorious for their reluctance to invest in new technology. But as the recession kicked in, so did Citrix’s business. As enterprise clients decided to wait on investing in more technology, small-to-medium businesses were pressured to cut back, says David Smith, Gartner’s collaboration analyst.

And so small-to-medium businesses looked toward the best technology solution to replace travel expenses and unnecessary overhead — at an affordable price.

“The SMB market was very much underserved in 2004 and 2005,” says Brett Caine, president of Citrix Online. “At the time, the existing options required a lot of training and the prices were unpredictable. That’s when we stepped in and saw our opportunity.”

Citrix’s lucrative success in the SMB market has garnered the attention of many of its competitors, which has also expanded its reach and focused on this segment. Specifically, IBM and Microsoft have made big pushes for SMB in the past few years, Gartner analyst Smith says.

For Cisco, more competition has driven the company to work harder than ever to maintain its market share dominance, says June Bower, vice president of Cisco Collaboration Software Group. After acquiring WebEx in 2007 for $3.2 billion, Cisco recognized the need to expand its client base in the market and is now fully armed to not only serve its existing enterprise clients but all the small-to-medium business clients as well.

As the tech giants look to expand their reach and try to appeal to both enterprise and SMB clients, Citrix will continue to focus on small-to-medium businesses, with the hopes of gaining more and more customers (this year the focus is abroad), and effectively, more and more market share. Ironically, despite not targeting enterprise clients, those companies are actually approaching Citrix, Caine says.

But will Citrix be a lasting success? Caine says that Citrix Online has no intent on moving toward a unified communications platform, unlike the rest of the industry. His argument is that his clients don’t want that.

Web conferencing is the leading web collaboration tool that both enterprise and SMB clients want after email, but actual implementation is slow, according to Forrester research. But right after web collaboration, companies also want video conferencing. So would it not make more sense to invest in a service that could provide a unified communications solution?

We’ll see. The market is still too young to tell. But Caine says Citrix is ready to adapt to whatever changes or demands his clients want. And if the company adapts its tools as quickly as it has grown, well, then this dark horse could win the race.