I have vanilla Mac OS X Leopard which comes with 1.8.6.
I am new to RoR so will be following tutorials on the net. Am I likely to find problems following them when using later versions of Ruby?
I am currently looking at this one which mentions 1.8.6 and 1.8.7 – http://www.railstutorial.org/book
The 1.8.x series (mostly 1.8.6) is still very much in widespread use and likely to remain that way for at least a year or so; 1.9 is slowly being transitioned to. Although there are some major differences between the two, for the most part everything you can do in 1.8 you can also do in 1.9.
Many of the trickier bits, like blocks and lambdas, get a bit of a makeover, but otherwise tutorials for 1.8 will still apply to 1.9 for the most part. You’re likely to run into issues if you use gems and libraries from 1.8 in 1.9, however.