It's perfectly legal, but it will still seem to some listeners like the sound of someone making off with England's crown jewels.

On Wu-Tang Clan's new single "The Heart Gently Weeps," a Santana-style rock guitar opening gives way to an almost celestial chorus of something very familiar. There, and throughout the track, is the unmistakable melody of George Harrison's timeless contribution to the Beatles' "White Album" from 1968: "While My Guitar Gently Weeps."

Now, the track is accompanied by Wu-Tang's trademark, uncompromising language, rapping out a gritty street story, even as Harrison's son Dhani plays along.

Meanwhile on the just-finished "Judas," Ja Rule is introducing the rap community to another incongruous musical motif. This is no unthinking appropriation of a classic act's creativity, as has sometimes been the case in rap. As he works at folding the original flavor into the hook of this midtempo treatise on "love, hate, jealousy and betrayal," he's doing so with the help of "Eleanor Rigby."

Forty years and more after the Beatles changed rock music forever, their songs have truly arrived in the 21st century as part of the rap/hip-hop art form--with the express permission of their publishers. Although there are hundreds of covers of "Yesterday," "Something" and the rest, this approach of "interpolation"--essentially rerecording a portion of a song--of the Beatles' compositions represents new access to the most famous catalog in the world. These developments may ultimately signal a fresh attitude toward Beatles masters appearing in everything from commercials to movies.

But don't expect to hear samples of the Beatles' original recordings, which remain strictly under lock and key, for now at least. Instead Sony/ATV, which owns all but a handful of the Lennon/McCartney copyrights, is allowing a select few to license some celebrated compositions and reference them in their own, newly recorded material.

Click here to find out what artists are interpolating the Beatles and how they're able to do it, as well as an analysis of the long and winding road of the Beatles' copyright ownership.