Carly Simon still isn't revealing who "You're So Vain" is about. But she's glad people want to know after all these years.

"It amuses me that I'm still being asked," the singer-songwriter says in a phone interview from her home on Martha's Vineyard, Massachusetts.

"You're So Vain" hit No. 1 in 1973, only about two years after Simon's solo career got under way. Since then, she's has had several more Top 40 hits, including "Nobody Does It Better," "You Belong to Me" and "Jesse"; has written music for a handful of movies, including the Oscar-winning "Let the River Run" from 1988's "Working Girl"; and has survived a bout with breast cancer.

A new two-disc collection of her work, "Anthology" (Rhino), compiles singles, album cuts and film work from her 30-year career across three labels. Simon also has released a holiday-themed album, "Christmas Is Almost Here" (Rhino). (Rhino is a unit of AOL Time Warner, as is CNN.com.)

When it comes to "You're So Vain's" mystery man, Simon, 57, may still be "playing possum," in the words of one of her album titles. But here's another clue: "There are always clues in other songs. The guy has repeatedly appeared in my songs," she says.

Ponder that.

Songs of revealing honesty

Perhaps people believe they can figure out the mystery because Simon's songs are so nakedly revealing of her often high-profile life.

Indeed, that life -- daughter of Richard Simon, co-founder of the Simon & Schuster publishing house; love interest linked to Cat Stevens, Mick Jagger and Warren Beatty; former wife of James Taylor -- and its play in the gossip columns have tended to overwhelm the straightforward honesty of her music.

Simon became a mainstay of the gossip columns thanks to some high-profile romances, including an 11-year marriage with James Taylor.

For Simon, being honest is the only way she knows.

"I was never aware of sharing too much in a song," she says. "It's a license to be as personal as you want."

"Anthology" shows Simon's growth and facility with changing styles. Early hits such as "That's the Way I Always Heard It Should Be" chronicle a woman taking stock of her freedom and independence. Then comes the lush, confident swoon of "Nobody Does It Better" (written by Marvin Hamlisch and Carole Bayer Sager for the 1977 James Bond film "The Spy Who Loved Me"), followed by the bitter recriminations of "You Belong to Me."

By the '80s, there's a maturity, expressed in songs such as "Coming Around Again" and "Let the River Run," while '90s tunes such as "Scar" -- a blunt song about her breast cancer -- describe the pains of age in sobering detail.

"I'm interested in detail, the vicissitudes of emotion," Simon says. "Maybe I'm more literally inclined [than I should be], too bombastic, but nuances are important to me."

Interestingly, Jac Holzman -- the founder of Elektra Records who signed Simon to her solo contract in 1970 -- wanted her to do cover songs. Simon had to prove herself as a songwriter. Fortunately for her, the first single off her first album was the self-penned "That's the Way I Always Heard It Should Be," and she was off.

Holiday album comes together

Simon tried to bring the same candor to "Christmas Is Almost Here," recorded with a minimum of frills by Don Was in Room 139 of Beverly Hills' Peninsula Hotel in January.

She was visiting her son Ben Taylor in Los Angeles and was looking for a reason to avoid flying back to New York right away, she recalls. She'd met Was backstage at Ben's concert and, during idle conversation, asked if he was free. Sure, said Was.

The next night, he called her. "What kind of album do you want to make?" he asked. Simon suggested a Christmas album, and suddenly she was making a Christmas album.

"We had five days, and no band, no place, no songs," she says.

Simon went to Tower Records and bought a slew of Christmas records, and a girl at a Sunset Boulevard music store sent over some music books. Was, ever the improviser, said he could engineer the album on his laptop in Simon's hotel room.

A band came together -- including special guests Billy Preston and Willie Nelson, the latter who had 17 minutes to sing on his own "Pretty Paper" -- and they got the job done.

Originally the record was just going to be distributed to friends, but after a little tweaking and a mastering job by ace technician Bob Ludwig, Simon decided to release it to the public. The album includes traditional selections such as "O Come, All Ye Faithful" and "Silent Night" as well as Simon's original "The Land of Christmas (Mary)" and a song she co-wrote with sister Lucy, "Heaven."

"Everyone was remarkable," Simon says. "Bob made it good enough to come out [commercially]. He put it over the line."

Simon's not exactly taking it easy right now. She's working on the music for two animated films, including one with Winnie-the-Pooh, and helping a friend who's in jail. That kind of activity is just the way she lives, she says.

"It's never changed ... from college until now," she says. "The two lines cross all the time. My personal and professional lives become one."