It’s been a long time since “Houses of the Holy.” But for those hoping to be able to buy Led Zeppelin’s iconic albums online, the wait will soon be over.

Led Zeppelin, one of the few remaining holdouts in the digital music age, said Monday that it is finally releasing its catalog digitally. The only official announcement from the group’s record label, Atlantic Records, which is owned by Warner Music Group (WMG), discussed how songs would be available through the V CAST music service of Verizon Wireless, the mobile phone service owned by Verizon (VZ) and Vodafone (VD).

But a spokesman for Warner Music Group confirmed to me Monday that other reports about Led Zeppelin’s music becoming available on other major music stores on Nov. 13 were true. That means people will be able to download “Stairway to Heaven,” “Kashmir” and other Zeppelin hits from Apple’s (AAPL) iTunes, Napster (NAPS) and RealNetworks’ (RNWK) Rhapsody for their MP3 players beginning next month.

This is big news for all the online music stores since Led Zeppelin, according to figures from the Recording Industry Association of America, is the fourth-biggest selling artist in U.S. history. Only The Beatles, Elvis Presley and Garth Brooks have sold more albums.

It’s also good news for Warner Music Group since it opens up yet another way for the company to cash in on Zeppelin’s back catalog. The big record labels may increasingly find that their livelihood will depend on nostalgia.

After all, Madonna, currently signed to Warner Music, is said to be close to leaving the company for a 10-year, $120 million deal with concert promoter Live Nation (LYV). And the rock group Radiohead, which is not signed to any label, turned the music industry on its head last week by offering its new album “In Rainbows” as a download from its Web site for whatever price customers wanted to pay - including nothing.

But by choosing to partner with Verizon Wireless, Warner and Led Zeppelin may be hoping to cash in on the fact that Verizon will also sell ring tones, wallpaper and other mobile offerings. And if you do the math, it makes sense to target both iPod customers as well as cell phone users who don’t own AT&T (T) iPhones. Verizon has about 62.1 million customers while Apple said in April that is has sold more than 100 million iPods.

When Led Zeppelin announced last month that it was re-uniting for a (supposedly) one-time only concert in London in November, I predicted that a digital music announcement from the band would soon follow, since the band’s label will be releasing a new 2-CD greatest hits package as well as a remastered CD and DVD of its concert film “The Song Remains the Same” in November.

And now that Led Zeppelin has finally agreed to join the 21st century, can the Beatles be far behind? Rumors of an eventual release of the Beatles catalog digitally have been swirling for years, but you still can’t buy “The White Album” and “Revolver” from iTunes. Maybe the Led Zeppelin news will push the Beatles to finally embrace the Web as well.