The lead that Nokia (NOK) and Research in Motion (RIMM) have enjoyed for years in the smartphone market is evaporating rapidly, according to a report issued Thursday by IDC.

Their immediate problem is Apple (AAPL), which shipped 18.7 million iPhones in Q1 2011, more than double last year’s shipments, to overtake RIM’s BlackBerry and come within 5.5 million units of Nokia’s Symbian smartphones. Unless Nokia manages the transition from Symbian to Microsoft (MSFT) Windows Phone 7 more smoothly than expected, Apple could overtake it before the end of the year.

But gaining even more rapidly are the two leading manufacturers of Google (GOOG) Android phones: Samsung and HTC. Their shipments increased 350% and nearly 230%, respectively, year over year, albeit from smaller bases.

In all, 99.6 million smartphones were shipped in the first calendar quarter of 2011, up from 55.4 million last year, with no sign of slowing down. “Conditions in the smartphone market are creating a perfect storm for sustained smartphone growth,” said IDC’s Ramon Llamas.

Last week, IDC reported that in the broader market for all mobile phones, smart and not-so-smart, Apple has taken the No. 4 spot and is growing faster than any of the other top manufacturers. See here.

Also on Fortune.com:

• Apple’s mobile share grew 78%
• Apple malware: 6 years of crying wolf
• Nielsen: Apple’s iPad still commands 82% of the U.S. tablet market

[Follow Philip Elmer-DeWitt on Twitter @philiped]