First a quick disclaimer. This applies to the schools and programs I'm familiar with. No idea if they're true of all schools in the USA little less schools in other countries.
I think there is also another way of looking at this topic. It's not so much how many jobs are available but how many jobs a person with a particular degree would be interested in and what those types of jobs are like. IMHO it's important for engineering students (or maybe any university student) to think along these lines on occasion and it's especially true of graduate students because decisions made early in a college career (and high school actually) can have long lasting effects on careers at varying levels of significance.
There are definitely more jobs appropriate and of interest to someone with a BS degree than higher degrees because their studies are less focused. There are typically fewer jobs for NCG's (New College Grads) due to the lack of experience compared to a BS in CS with five years of work experience in the computer industry after graduating and the later will usually command a higher salary.
When someone starts on the path of graduate degrees subject areas start becoming important. At the Ph.d level those and the subject of their dissertation and published work is all important. A Ph.d with graduate work in queuing theory is not going to be looking at an entry level jobs working on PC's in an IT department, but when he or she applies for the appropriate job at a firm working on telecommunications or operating systems, then they may find themselves welcomed with open arms, a generous starting salary and perks the IT guys will never see unless they are high level managers. My point being that someone who is on a graduate degree track is (or should be) aiming their academic career in the direction they want to follow after they graduate.
Another thing to note for NCG's is that the alma mater may matter. Early in one's career recruiters at engineering companies will often consider alma mater to be a significant difference and a degree from MIT, Purdue, UCLA, etc. will be a major issue when compared to degrees from smaller state schools for instance, especially if that school or it's engineering department is not accredited by the appropriate body. IMO, as one's career continues experience becomes more important than the school over time.
I think it's important to point out that degrees may come from different colleges in different universities. For instance, Computer Science degrees usually come from the College of Engineering's Computer Science department or sometimes EE department or occasionally the College of Letters and Science Math department. Information Systems degrees tend to come from the Business school. And extension classes typically have nothing to do with the degree programs and are separate from the actual university, they just use the university facilities. Although the classes can have transferable credits and the extension programs make a big deal about working with university and what not, IMHO although that may be true a lot of that is marketing. If the work is technically focused, software development of compilers for instance, in that case many shops will be looking for a CS degree, not an IS degree. Likewise, although a CS degree and an ECE degree may overlap there are also parts of both degrees that are not intersecting that might be important for a particular career path.
Finally, it seems like the less education and training a job requires the more likely a US corporation will offshore the job. That's not a hard and fast rule, but it seems like jobs such as help desk jobs were among the first to go. Certainly whether or not a job required touching something (e.g. repairing PC's) makes a difference, but at businesses I'm familiar with that amounted to whether the work was off shored or outsourced. The later is still a job, but depending on the outsource company it may not be as good as the insourced job was.
Degrees may not be essential for long-term success, but they usually don't hurt and IMO they usually increase the chances. Unfortunately, it's often hard to see if the grass is actually greener on the other side of the fence until after someone has been working a couple years at which point it turns into a catch-up situation (which isn't the end of the world but that is another thing that can have undesirable long term repercussions IMHO).