First of all, we'd all surely be willing to call "life" a form of nondiscrete chemical dynamics – basically a noncellular, continuous network. Like the Lem's Ocean, basically. One good place is any sort of physical interface where concentrations of chemical species are high: a solid-fluid interface in a planetary body would be great; something akin of the montmorillonite-bioplasm model of abiogenesis. A contact between a disequilibriated pool of chemical species and a porous soft rock has a great potential for metabolic-like activity, also for genetic-like selfconstraining based on the correspondence between platey/linear silicon and carbon polymers (clay-hydrocarbon is a good example). Such networks could easily evolve and it's not difficult to imagine organelle-like entities yet no cells at all. A form of life like that could have no superstructure at scales exceeding an inch – and would still be able to react to environment via photochemistry and "compute" in a neural-network way. The whole idea of sending messages outside this system would be preposterous for an entity like this which would literally float in its own feromonal soup. It would not emit EM signals, and would it decide to colonize other habitats, a preferred form would be something like a dm-sized interstellar grain coated in ice, ready to be incorporated in a future Neptune or Enceladus. The SETI program doesn't much cover that, doesn't it?

A second good example – which is one of my personal favourites – is a solely mineral-based form residing at an interface between the molten chamber and the solid rock. Not many people know that silicates polymerize as neatly as carbon does and that any good old Hawaiian lava bit is actually an extremely fidel network of silica-based chains with considerable side-chain differentiation. The problem with mineral life is its slowness, but not at high temperatures. There are also many more levels of freedom that you would expect. Trace elements can provide fine-tuned chemical and suprachemical properties and also change thermodynamics properties of the minerals so that the controlled release of latent heat by different minerals could arguably be a good point for starting metabolism. Furthermore, paramagnetics (if we're talking above Curie point here) can respond to EM field of the magma chamber which could – if we allow ourselves for a littler more extravagance – then self-influence through the construction of rock-structural units modifying the flow of dynamo-inducing fluid. That's almost like a brain now. Such life would be buried deep in rock, is imaginable at the core-mantle boundary here on Earth but also basically everywhere where there's rock and heat – hence everywhere. It also does not result in any discrete "organisms" that could "pack themselves" into spaceships. Yet there are imaginable forms of reproduction for these that would be surely left unnoticed by green-men-seeking people.

So in short, seeking radio signals to find intelligent life is probably the best we can practically do (yet looking for signals of nonracemity is a good bet to me), but it's no more intelligent and anthropocentric than looking for spectroscopic signatures of flyers advertising a good pizza-bar floating in interstellar space. Also, I don't buy Your, Pamela, bet, because there are no good astrophysical reasons for rocky planets like ours not forming 5, 6, 7, or even 10 billion years ago, as long as there's enough metals in a given cloud for ONE. Since the Pop III stars there's enough for ONE, so it's enough for life like our own. So I don't see why life would suddenly begin forming 13.7 billion years after the BB all over the place. Nah. That's not an answer.

Life is like a lump of clay that's been shaped and animated with an entangled breath of intelligence … the intelligence is everywhere, and the clay (like gold) is where ever you find it …