Just lost most of my day trying to install Oracle 11g onto Ubuntu 11. In case you're curious (and mostly, for my future reference), this forum post was VERY helpful.
It's sortof sad that there's no official documentation from Oracle for doing this. And that their distribution for "Linux" is an .rpm. And that in many cases, when the server fails to start up, it doesn't bother writing any logs to let you know why. And... bleh, I'd go on but I have to go cut myself.
It's developed and tested on RedHat. Even Oracle's linux is an older version of RedHat Enterprise. Ubuntu folks had posted warnings about Oracle issues before... Just glad I've never had to deal with Oracle. =)