The Apple chairman and CEO said the new Nanos use arsenic-free glass, are free of BFR, mercury and PVC and are highly recyclable.
"This is great news," said Casey Harrell, a toxics campaigner for Greenpeace International. "They've been moving this way on the design side of their products."
In 2004, Greenpeace started targeting the technology company with a "Green My Apple" e-waste campaign. When Jobs publicly committed to creating more environmentally sustainable products in the spring of 2007, Greenpeace dropped the campaign.
Harrell said Jobs agreed that, starting Jan. 1, 2009, the company would create products free of BFR (brominated flame retardants) and PVC (polyvinyl chloride).
"They're beating their deadline, hopefully," he said, adding that Greenpeace will still be watching to make sure that subsequent iPhones, MacBooks and desktop towers will be as clean.
Independent analyst Rob Enderle said Apple's new announcement signals that the company is "finally stepping up and starting to embrace the green movement."
"This was a huge embarrassment, continually highlighted by Greenpeace," he said, adding that the situation looked even worse because former Vice President Al Gore is a member of Apple's board of directors.
Despite this victory for environmentalists, analysts said the presentation included few surprises.
"[There was] no revolution," said James McQuivey, a principal analyst with media research firm Forrester Research. "There's obviously evolution in that the devices are moving to a better experience, but there's nothing here that changes the game."
"Anyone expecting Apple to make any move that would dramatically alter the field would be disappointed."
Avi Greengart, an analyst with Current Analysis, also said that many of the features Jobs revealed today had already been seen on rumor blogs.
But Greengart said he was impressed with the new Nano that he said combines the best of the second and third generations.
The new, thinnest-ever Nano marks a return to the slim and tall design analysts say consumers liked better than its predecessor. The third-generation version offered crisp video but was wider and shorter.
The fourth-generation version announced today also includes a "shake-to-shuffle" feature that allows users to lightly shake the device to activate the shuffle mode.
"You have to see it in person," Greengart said. "You have to actually hold one. It has the screen from the Nano from last year and the lost-in-your-pocket feel."
"Every year Apple comes out with something new and exciting and continues to maintain an extremely high market share. ... This is why," he said.
As analysts expected, Jobs also announced a new update for the most recent iPhone that he said would fix a number of bugs. Since its launch in June, the iPhone 3G has been plagued with numerous complaints from new owners and has been the target of two lawsuits.
The update will be available Friday and is intended to improve battery life, reduce the number of dropped calls, address crashing problems and increase the speed for iTunes backups.
Independent analyst Rob Enderle said this update should finally make the iPhone 3G better than the original version.
"My understanding was to not buy the new iPhone until this update came out," he said.
Jobs also announced a renewed partnership with NBC that will make the network's programs available in high definition and standard definition and an updated iTunes application.
ITunes 8 includes a new "Genius" feature that automatically creates playlists out of a user's music library.
"It's probably easy to underestimate the power of the Genius application," analyst McQuivey said. "This is an area that Apple has neglected for a while and has ground to cover."
"If they can do this in typical Apple style, they should be able to drive up listening hours and that translates into future sales."
