Lots of ruby/rails developers are Mac users so I thought this might be
of interest here.
Here are some bumps I've had in the upgrade.
1) If you are using any macport installed software, get a list before
$port installed > myports.txt
You're going to need to get the latest Xcode and macports and
reinstall al of your ports. I couldn't get a list of ports after I
reinstalled macports, and port wouldn't work at all before I did.
Don't know if this is similar if you use fink, since I don't use it.
2) Backup any crucial mysql dbs before the upgrade. Luckily for me I
didn't have any CRUCIAL dbs.
3) Not exactly sure about this one, but I found that after the
upgrade, I had rubygems 1.2.0!!!!!! and it couldn't be updated to the
latest. Not sure exactly why, since I ended up installing ruby and
gems from source, which is what I normally do since I prefer to have
control over what version(s) I'm running and not be dependent on
Apple. I do the same thing on my linux system.
My theory as to what happened here was that since I'd bypassed the
ruby install on Leopard by symlinking from /usr/bin to the source
installed binaries, the Snow Leopard install got confused and I ended
up with the old Leopard installed rubygems being active. But I'm not
Forewarned is forearmed.