Yes, I am still reading the fine new Leonard Cohen bio and just got to the, ahem, famous episode with Janis Joplin, shortly before her death. Leonard wrote about the epic bj he allegedly received from her there while her "limousines waited in the street" in his great song "Chelsea Hotel." He didn't ID her in the song but later did in interviews--one of the very few cases in his long life when he was not a gentleman, as he has admitted.
Many may not know that there are two versions of the song. The one released and always performed live is "Chelsea Hotel #2" but there was an earlier "Chelsea Hotel #1" which he only did live. It still mentions the bj but is much longer and much sweeter about Janis overall. After all, #2 ends with him saying he doesn't really think of her "that often." Here's the obscure #1 live below.
BTW, what I also learned in the book was that Joni Mitchell wrote "Chelsea Morning" (which inspired the naming of Chelsea Clinton) while living with Leonard there. Also, Leonard might have slept with Edie Sedgwick there. Finally: He stayed for awhile in the room there where Sid killed Nancy.