Just a quick hit on this, since I've been revisiting some old recordings of this cool tune. Antonio Carlos Jobim, its composer, hopefully needs no introduction -- and if you don't know who he is, you have probably heard a couple of his more famous compositions. The Instituto Antonio Carlos Jobim (what I gather is the official Jobim museum in Rio de Janeiro) gives the title as "Favela (O morro não tem vez)," although Jobim's original copyrighted melody (1962) is just in the Portugese title. "O morro não tem vez" translates to "the hill has no time," or something like "there are no opportunities in the hill," though I have also seen recordings of this titled "somewhere in the hills," which is where a favela would be (favelas are slums, which are up in the hills surrounding Rio). (sidenote: anyone who feels like learning it and/or studying the arrangements can see all the original manuscripts at their online archive! #librarianenvy)
As far as I can tell, the first American recording was by Stan Getz with guitarist Luiz Bonfá (and Jobim) as "O Morro Não Tem Vez" on his Jazz Samba Encore! album, made and released in early 1963. Jobim recorded it a couple of months later for his own American debut, The Composer of Desafinado Plays, then again with a bigger orchestral arrangement for his second album. Sergio Mendes (pre easy listening) also recorded it in 1965 for his American debut, The Swinger From Rio, and I can't resist pointing out this lesser known but totally cookin' trio performance also from 1965 as well; wrap your head around that bass/drums intro! There were probably more as well. Martin Fierro seems to have brought the tune to the Garcia/Saunders band, so I presume that he heard it on Stan Getz's record. G/S play it in the same key as Getz, as well.
The first time Garcia played Favela, that we know of, was 8/15/74. The band played it at nearly every show through December, and then it was played periodically, but far less, by the Legion of Mary. Paul Humphrey plays the shit out of it on nearly every version, many of which are quite fast and pretty damn furious. They really bit down on it every night.
The original recordings, by contrast, are at a much more languid tempo. I strongly recommend both Getz's Jazz Samba Encore and Mendes' Swinger From Rio to anyone who enjoys this kind of jazz, and both are a perfect fit for the waning days of summer.