if you watched sesame street as a kid, this phrase will either bring back warm memories or send shivers down your spine (depending on how you feel about muppets, i suppose =): "today's show was brought to you by the number 3 and the letters 'n' and 'p'. sesame street is made possible through the support PBS..."
whenever i look at a kde application a similar thought runs through my head: "this application was brought to me by this application and the kde, qt and x.org projects". yes, that's a simplification, but the idea is clear: our applications don't stand as lone monuments to the application developer's work. they are both part of something bigger (a whole universe of cool apps!) while also made possible by the efforts of those working on the platforms on which they rest.
if you are a kde application developer, perhaps take a moment over the holidays to look through your code and see all the K's and Q's in there. and if you look deeper into the libraries those letters came from you'll see other letters like X.
for me, there are two really important things here. first off, when i write an application i have something of a duty to the platform i'm using. when i diverge to afar afield, i'm actually not doing anyone aside from my ego a favour. when i don't send my Cool Amazing Generally Applicable Techqnique(tm and copylefted, patent not pending) down-stream so that other app developers can benefit and help me maintain it, i'm also losing out. kdelibs would not be where it is today without these concepts.
the other important bit for me is that spending some time working on the foundations is really, really valuable. applications are what defines values on a platform, but without a solid platform you don't get valuable applications. it's a virtuous circle.
right now, however, that virtuous circle is breaking down. and not just in kde. tim janik wrote a really great blog entry today abut the unfortunate state of maintenance in gtk+. i really recommend reading the email tim sent to the gtk devel list on this same topic. there are some truly sage points in that email and it is as applicable to kdelibs as it is to gtk+.
it really doesn't take much, either. even helping maintain just one class or one set of functionality goes a long, long way. every lib hacker has the support of the others and it doesn't take a huge time commitment, just a little time here and there consistently. those who do put in large amounts of effort are also welcome and needed, of course, but that isn't the only way to be involved in a meaningful manner. and when you are involved in a meaningful way with the libs, every application benefits including your own.
this tuesday is "libs monday" (due to monday being a signficant holiday for many people, so we moved it ahead one day so as to work around that) and much of the work i'll be doing could be done by anyone with a bit of direction and an svn checkout of kde4. even if libs mondays don't work for you time-wise, pick any day or time that works for you and find us on #kde-devel or #kde4-devel and there's probably someone there than can help with your questions and what not. the usual mailing lists (kde-devel at kde dot org being the most common one) are also at your disposal.
by getting involved we'll continue to be able to say for years, even decades, to come: "these apps were brought to you by the developers of the application and made possible by the support of the kde project..." =)