What's the point of living at all if not to explore?
Do we just be born, make babies, and die, ad infinitum until some cosmic catastrophe wipes us out permanently?
We're doing what we can with the exploration of local planets, and it is a worthwhile endeavor, but SETI is the only program we have which is even capable of saying "Yes, there is intelligent life in this Universe besides us." The dizzying prospect of answering this question at all makes SETI one of the most important exploration programs run today, in my opinion.
Personally, I think we're not doing enough and should be devoting more energy and resources to broadcasting directed, long-term, repeating messages toward high-probability target systems. Maybe everyone out there is listening and no one is broadcasting. Our omnidirectional radio broadcasts are diminishing greatly after only a few decades of having the technology. Let's take the initiative and let the Universe know that we're here in no uncertain terms. Consider the few messages that have been sent so far. If those messages were detected by SETI, would they even qualify as a hit? Would those messages be interpreted as just another "Wow!" ? (edit: It appears Active SETI has done just this a couple times -- though with few repetitions. Hopefully that's enough!)
Amb makes a good point about when the detection may happen. Unless there are projects in other systems to send out a continuous pulse saying "we're here," then we're unlikely to hear anything but a reply, which will take many years to arrive. A more likely scenario than picking up a stray, repeating radio signal is that other civilizations are listening, just like us, and when they detect a faint signal from some direction, they shoot a focused "we hear you" right back.
I also think we have an obligation to reply with a clear message of "we hear you" should we ever detect a stray signal.
Apologies if this has been covered already, I didn't have the time at the moment to go over 24 pages of posts. =) I just wanted to throw out my position (and creep a little closer to 50 posts

).
edit- I just noticed the discussion of Active SETI. Fantastic. =)