HP also must still attract an army of software developers to build applications, Kay said.

But HP insisted webOS will be an attractive target for developers. The company claims to sell, on average, 120 printers and 120 PCs every minute. "You do the math on two PCs a second and two printers a second," Bradley said. "You easily exceed 100 million Web-connected devices annually."

And despite Apple's early lead, the market for tablet computers is still young. "We're still in the early stages of a market that's going to continue to grow in size, importance and relevance," Bradley said.

Agam Shah in New York provided additional reporting.