Why I'm interested in Go
These days, my substantial programming takes place in one of two languages. I use Python if I'm dealing with something that doesn't have to run fast or use minimal memory, and I use C on the occasions when Python doesn't fit. I like C, but it is a very sparse and unforgiving language when compared to Python and this translates to slower and more annoying development most of the time; there's a lot of low level details that I have to worry about when I just want to bang out some code that runs fast(er).
(This annoyance leads me to use Python for everything that it can even barely be made to fit.)
There are times when C is the right answer, but there are also a lot of times when what I want is in the middle between C and Python, problems where Python is too heavyweight and bare C is too low level. Part of why I'm interested in Go is because it seems to be the most promising candidate to fit in this niche on Unix. It promises relatively fast runtime and relatively little memory usage while still giving me garbage collection, convenient strings, hashes, and arrays, and a decent set of support modules. For me, this makes Go the attractive choice for writing various system level programs like non-trivial network daemons.
(There will be C libraries for all of the packages that Go comes with, but I'd have to go find them and that leads to the selection problem. And in general, syntax matters and Go has better syntax than C plus libraries.)
Another part of why I'm interested in Go is that it comes from a group of people (call them the Plan 9 crowd) that have created a whole bunch of interesting, good ideas that I've found attractive in the past. Sometimes the results are too purist for my tastes, but they've pretty much always been worth a look. And the way I look at languages is actually using them for real work, so I have gone and dabbled in Go; ideally I would like to use Go to write a relatively substantial program that I'll actually use.
(It has to be a personal program, since I won't write production programs in obscure languages that my co-workers have never heard of and that don't (yet) come packaged on our Unix systems.)
Sidebar: why other candidates are out
Java is, right now, not a particularly great language to write Unix system programs in for at least two reasons. First, Java programs generally start slowly for the same reason that Python programs start slowly; they have to load and start the interpreter before they actually start the program. Second, my impression is that the JVM does not provide good access to Unix systems facilities.
(These drawbacks apply to any number of interesting languages built on top of the JVM, and in general to any interpreter-based language. Slow startup is not an issue for long-running programs, but I don't write that many of them.)
The D language struck me as sort of interesting when I first heard about it but it doesn't seem to have cohered into a useful system (rather the reverse, in fact), and I'm not really interested in languages that aren't open source because there's very little chance that they will become popular on my platform of choice.
C++ has many of C's problems as far as language features go, just somewhat nicer syntax once I find libraries and packages and so on that do what I want. And it doesn't have native garbage collection, which is one of the great programming speed accelerators.