I use IDEA-9 under MacOS (Snow Leopard) at home as well as under Ubuntu Linux 9.10 at work. It's very easy to use IDEA with Ubuntu since I am a power Unix/Linux user and have been for a long time. I simply download the tar.gz bundle and set up a symbolic link to point to the new install location. I also keep the older version (currently I have a copy of IDEA-8 just in case IDEA-9 misbehaves).
Under MacOS, JetBrains simply offers the IDEA package. What is the best way to upgrade from IDEA-9 to IDEA-9.0.2 and keep one older version as well (if at all possible). If I download and install the new 9.0.2 package for MacOS, will my existing installation get deleted? Although MacOS is wonderful and very usable (everything works unlike multimedia issues with Linux), I often get upset when I can't do real Linux like stuff.