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Looking at Apple's current offerings, I expect to be purchasing a Mac Pro with OS X Lion. I have no experience with Mac OS X (see Background below for other details).
Based on you're background, I think you'll be fine (FreeBSD, Solaris etc.). Open up Terminal (command line), drop it in to your dock for quick access and type away.
In order to build perl/modules, it seems I need to first install Developer Tools (following advice found in Installing make on mac LION osx). Anything else?
You can work with the system Perl but it's generally recommended to install a separate version for your own work. In the past version both 5.8 and 5.10 were installed and there were issues with some people due to support for both 64 and 32bit for example. Those AFAIK are no longer a problem but you are still using the system's Perl. It does use it and if you mess around enough - you won't be happy. If Xcode get's an update that makes a change to the Unix tools that mess with the @INC path, you wont be happy. So, again, you may want to install an alternate version from Activestate.
That said I never had any significant problems. If you don't plan on using Xcode for anything other than a compiler and your modules are installing fine you can always skip the updates.
You will also want to install Macports. There are a number of Unix tools and libraries that are not included on the Mac. I don't know what field you're in or interests are but for example, there are some graphics and GUI libraries that are not included. It's pretty straightforward to use Macports but will be an extra step.
"...the adversities born of well-placed thoughts should be considered mercies rather than misfortunes." — Don Quixote
In reply to Re: Are there any major Perl issues with Mac OS X Lion?