Okay a more thoughtful post, here we go:
I think that for immortality to exist we'd have to a) have solved the issue of scarcity and b) have found ways to curb population growth simply to preemptively address issues of overcrowding. So to have a hypothetical conversation about the societal ramifications of immortality, we'd have to consider those two things as being givens.
Assuming that, the picture of a life lived without end (or, at least, with a nebulous end that can be defined and accepted by the person rather than being out of their control) changes pretty drastically. With no scarcity, the concept of "jobs" and "careers" gets a bit sticky; if things aren't scarce, how does our economy work? I'd imagine it becomes motivated by cultural and intellectual capital. What sort of work can you produce that improves the body of work of all of humanity? What art can you create, what contributions to science can you make, what ideas can you propagate? When an entire life is spent not earning a living, but rather accepting that living as a given and using it to embark on creative endeavors, I can't help but wonder whether or not one would even want to "end" their life. I feel like when you grow up in a world that accepts this sort of immortality and encourages cultural and intellectual growth, there can be no "boredom" that people often assume is inherent with immortality. You pursue creative endeavors endlessly, or intellectual ones tirelessly. There's no slavish work week keeping you bound to an exhaustive schedule; you are driven forward not by a desire to stay alive and eat, but solely by the passion of creation and discovery.
On a parallel axis we have the question of romance that Repentance brought up; how exactly does monogamy work when you have essentially endless life? Again I think the answer is very simple: it doesn't. Monogamy has its evolutionary roots in child rearing, and assuming that we have ways to curb population growth, child rearing is likely not a particularly common thing, occurring at the same rate that people choose to die (or that people who reject immortality die naturally). So, given enough generations passing, I think the nexus of human romantic relationships will shift dramatically. Where it lands is an interesting question, and it's tempting to assume that it shifts to being focused on sex-for-pleasure, which would certainly be an interesting system (I imagine it would end the idea of prolonged partnership entirely and possibly even pave the way for widespread casual sexual encounters among friends). But I think there's little question that monogamy as we know it would basically be a relic of the past, and while people would certainly have incredibly close partnership and friendship, the idea of a sole significant other would probably be gone.
The big thing about all of this is, of course, that societal change of this magnitude takes a lot of time and takes place over many generations. With people living presumably indefinitely... would enough generations be able to pass to bring it about? Or would enough people from our modern society continue living and remaining relatively static, keeping the world in a bizarre state of half-change? It's been over 150 years from the end of slavery in America and we still aren't anywhere close to racial equality in this country; how could we expect a complete overhaul of the economic system that has lasted all of human history to be a smooth transition?
Immortality is cool and all, but I get the feeling it may be self-defeating - creating a circumstance where society needs to fundamentally change, but because people aren't dying and new generations aren't taking the reins, it might not happen.