What versions of rails and ruby were you using on Ubuntu, and Mac os X?
I don't think you should have to do anything specific. I use mac OS X 10.6.4 for developing and it's been very easy to set up and get running. The only thing I had real troubles with on Mac OS X was installing and configuring mysql. The problem lies with versions of different stuff.
Snow Leopard comes with Ruby 1.8.7 x86_64 (64 bit ruby). But I've seen that a lot of people still recommend using MySQL 32 bit, because the mysql preference pane is 32 bit only and screws up with 64 bit MySQL (not sure how so, I haven't seen any ramifications of it yet). So I downloaded and installed mysql 32 bit and it didn't work. Why? Because by default snow leopard has a 64 bit version of ruby. So then I uninstalled MySQL 32 bit and installed the 64 bit version. I could have uninstalled ruby and reinstalled it with a 32 bit version but I chose not to.
I've got it up and running just fine now. I wrote a tutorial on how to set up and configure MySQL and phpMyAdmin in the tutorials section.
If you aren't using mysql then I guess none of that's relevant. But the other thing I had trouble with recently was sqlite3 1.3.0, so I turned around and downloaded 1.2.5. However, there has since been a newer release of sqlite3 (1.3.1, which may have fixed 1.3.0) as well as sqlite3 experimental version. Maybe you downloaded one of those. I wouldn't know about those versions.
Last edited by RailsRhino (2010-07-30 12:08:39)