It isn't something I want and crave for constantly, but right now it is definitely a desire of mine. I have had my current bike for years and while it isn't in bad shape, it certainly isn't in top condition anymore. The poor thing has seen a lot of travel - like Susimi's, it has been along everything from gravel roads to muddy trails. If I had the money to get a new one currently I certainly would, but it is sadly not something I can reasonably afford. Living off a small wage topped by small amounts earned online doesn't leave me with much to spend in surplus.
Overall though, I don't feel a constant need to have the latest model, no. Even just getting my current bike fixed up a bit would be great for me. I don't see a need in getting a new one if I don't need it yet. Astronomical difference, I know, but getting a new bike at on a whim is basically the equivalent of getting a new car just because it is something I want - aka, not doable. So I just don't think about it.