Winslet offered a tribute to the late Anthony Minghella and Sydney Pollack, both producers on "The Reader," and said 2008 was a fabulous year for films.
"It's really an honor to be included in what I think is such a remarkable year," Winslet said. "I really feel like everybody should be given a medal."
The role already earned Winslet the same prize at the Golden Globes, where she also won lead dramatic actress for "Revolutionary Road." But at the Oscars, Winslet has just one nomination, as lead actress for "The Reader."
As it did at the Golden Globes, "30 Rock" swept the TV comedy honors, Tina Fey and Alec Baldwin taking the individual acting prizes and the show winning the ensemble cast award.
Fey, creator and star of the series set behind the scenes at a sketch-comedy show, lobbed a wisecrack at Hollywood producers, who have battled Hollywood trade guilds over actors, writers and others' share of potential profits from Web programming.
Joking that one day, her young daughter would be old enough to watch reruns of "30 Rock" on the Internet, Fey said, "She'll look up at me and say, `What do you mean, you don't get residuals for this?"'
Hugh Laurie, won his second straight SAG prize for best actor in a TV drama for the medical show "House," joked that he was disappointed one of his fellow nominees did not win.
"I actually had a hundred dollars on James Spader (of "Boston Legal")," Laurie said. "This is just not my night."
Sally Field earned the TV drama actress award for the family series "Brothers & Sisters," while the advertising saga "Mad Men" was named best drama show. Accepting alongside his cast mates, "Mad Men" star Jon Hamm had kind words for the show's "dozen of viewers."
James Earl Jones was honored with the guild's lifetime-achievement award for a career that included roles in "Dr. Strangelove," "Field of Dreams," "Cry, the Beloved Country" and "The Man," in which he played the first black U.S. president.
The ceremony featured clips highlighting Jones' rumbling bass voice as the mouthpiece of "Star Wars" villain Darth Vader, the noble patriarch in "The Lion King," even cable news with his "This is CNN" announcements.
"I want to thank you for all the work that you do," Jones told the audience, quoting the Book of Genesis on how God breathed life into man. "I don't mean to embarrass anybody by comparing the actor to God, but once we've taken the role, we have a similar responsibility to breathe life into that role, and only the actor can do that."
Before the show, "The Dark Knight" won SAG's honor for best movie stunt ensemble on Sunday, while "Heroes" took the same prize for television.
The stunt honors were announced on the red carpet as stars were arriving for the awards, one of Hollywood's last big ceremonies on the road to the Feb. 22 Academy Awards, whose nominations have lined up to make the SAG honors a real prelude to the Oscars.
Just three days before the SAG Awards, the Oscar acting categories came out virtually in sync with the guild picks, with 18 out of 20 performers competing for the same prizes at both shows. The lead-acting categories feature the same people in the running at both shows.
The late Heath Ledger loomed large at last year's ceremony, his death coming just five days before the SAG Awards. Actors spoke reverently of him, and Daniel Day-Lewis dedicated his best-actor win for "There Will Be Blood" to Ledger.
This time, Ledger is viewed as a near lock to win the supporting-actor honor for his ferocious reinvention of Batman villain the Joker in "The Dark Knight."
Nominated for overall cast performance are four of the five best-picture Oscar contenders: "The Curious Case of Benjamin Button," "Frost/Nixon," "Milk" and "Slumdog Millionaire."
The fifth SAG cast nomination went to "Doubt," while "The Reader" has the fifth Oscar best-picture spot.
While individual categories at SAG are a solid forecast for who might win at the Academy Awards, the overall-cast category has a spotty record at predicting the Oscars.
"No Country for Old Men" won at both SAG and the Oscars last year. But winners in those categories have lined up at both shows just six out of 13 years since SAG added the cast honor.
