The iMac is a relatively low cost PowerPC based system. It comes in a nice integrated package with a fairly small profile. The hardware itself is very quiet and makes a very nice desktop system. The newer iMacs come with a wide variety of connectivity options including wireless support (through an optional card), Firewire (1394), USB, 56k modem (which may be incompatible with Linux) and 10/100 ethernet. You can buy an iMac and thats it, no need for any additional equipment.
Thats nice and all, but why would any sensible Linux user turn in their 1GHz Duron and three button mouse for a 500MHz-800MHz iMac G3 or G4? Well that really depends on what you want to do. Linux on the PowerPC (in particular the iMac), is well supported and the majority of things you would expect to do under RedHat you can do under other distributions for the PowerPC such as Yellow Dog. The two factors that make the iMac really attractive is its PowerPC based processor and its low price.
The Motorola G3 and G4 PowerPC processor is a 32 bit RISC based processor. Most modern processors are either 32 bit or 64 bit. Intel's Itanium processor is an example of a 64 bit processor. 64 bit processors tend to be more expensive than 32 bit processors. AMD's Duron and Athlon processors along with Intel's Celeron and Pentium III/IV processors are all 32 bit. The PowerPC processors are RISC based, RISC means that a CPU has a reduced instruction set. Processors understand certain instructions, and programs are generated from grouping those instructions together to perform a task. The idea behind a RISC processor is that a smaller instruction set results in faster execution. Intel and AMD processors are not RISC based, they have larger instruction sets however, larger instruction sets depending on the task at hand can execute certain operations in a single instruction while RISC processors may take several instructions to complete the same task. The tradeoff is that the RISC processor maybe able to process the simple extra instructions fast enough to compensate for the lack of additional instructions. The PowerPC processors also have a shorter pipeline. When comparing processors it is important to consider the entire system, processor design, speed, cache and so on.
IBM and Motorola manufacture PowerPC processors. IBM systems that use PowerPC processors tend to be expensive compared to Apple® hardware. Old classic MacOS 9.1 is several steps short of a UNIX operating system, MacOS X is a step in the right direction but we think Linux does a better a job. Linux of course is also free. Taking the PowerPC based iMac and combining it with Linux provides you with a very low-cost PowerPC based unix system, giving you access to the hardware platform that without Linux would require expensive Unix servers.
For developers, the iMac is pretty useful, especially if you are working on a G3 or G4 based embedded device. The iMac can provide you with a place to test out your code prior to deploying it on flash or other media.
The iMac is NOT ideal for anyone who needs a very high resolution screen (higher then 1280x1024 on the iMac G4 or 1024x768 on the iMac G3) or a large screen (larger then 15" LCD (equal in viewable size to 17" CRT) on the iMac G4 or 15" CRT on the iMac G3). This maybe too small for power users and anyone who wants to do graphics or video type work. If a larger screen resolution and a selection of your own screen -- ie. a really large one, you should look at the PowerMac G4 series.
The iMac provides low-cost access to the PowerPC hardware platform. It provides a nice integrated desktop solution and has a small profile. It has a wide variety of connectivity and external expansion. Due to a lack of fans, extended periods of use (eg. as a server) are not recommended without some form of additional cooling. Maximum screen resolutions and small screen size may be a problem for some users. For a first time computer buyer who is also interested in Linux it is a good buy.