For Jessica Rodriguez, waiting four days for an iPhone is nothing when the prize is "the next big thing."

On Tuesday, Rodriguez became the fourth person to line up outside Apple Inc.'s (AAPL ) Fifth Avenue store in New York.

The 24-year-old college student wants to get a belated birthday gift for her sister as soon as the iPhone starts selling Friday evening.

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"Words can't express why I want an iPhone," Rodriguez said, sitting in a red folding chair she brought. "The main reason is (Apple CEO) Steve Jobs is a genius. He's a great innovator. It's going to be the next big thing in cell phones."

The three people ahead of her all joined the queue Monday, braving temperatures that reached 90 degrees. Their spirits weren't dampened by forecasts for thunderstorms later in the week and remarks such as "Crazy, people are just absolutely crazy" by one passer-by.

David Clayman, 21, on vacation from Chicago, happened to walk by and decided to change his travel plans on the spot, extending his trip by a day.

He hopes to buy three phones: One to raise money for charity; one as an early birthday gift for his dad, who turns 50 on Saturday; and a third for himself.

Apple isn't saying how many units it will have at launch, nor has it announced any per-person limit.

The iPhone goes on sale Friday at 6 p.m. in each time zone. Besides Apple's retail stores nationwide, the phones will be available through some AT&T stores and through Apple's Web site. AT&T Inc. (T ) is the phone's exclusive wireless carrier in the U.S.

Amazon.com Inc. (AMZN ) already is taking pre-orders for books related to the iPhone, while the online classified site Craigslist had listings from people willing to wait in line for cash or looking for someone to do so.

People have waited days in line for movie premieres and for video game consoles , but for a phone?

Apple claims the iPhone — which combines the functions of a cell phone, iPod media player and Web-surfing device — will be easier to use than other smart phones because of its unique touch-screen display and intuitive software that allows for easy access to voice mail messages, the Internet and video and music libraries.

Those features interest Eric Mueller, 45, a graphic designer who joined the line after dropping off materials for a client nearby.

He said he looks forward to better compatibility with Apple's Macintosh computers, complaining that the Bluetooth wireless connection on his Samsung Electronics Co. phone hardly works with Macs.

But Mueller said he might not last until Friday, saying every hour waiting for a phone is an hour away from serving his clients.

Others, though, were willing to tough it out.

"I've met some incredible people waiting on line," Clayman said. "When are you going to get an experience like this?"