I'm not sure they'll be humanoid, Rob. There's no reason they can't be, of course, but active, tool-using creatures can probably come in a variety of shapes, as many SF writers have imagined. I believe humanoid would be a very lucky coincidence. I've always imagined a centaur-like creature, two limbs for walking, two for grasping, and two in between capable of doing either, but not as effectively as the other two pair. Insects manage to control six limbs (more, if you count antennae and labial appendages) with very simple nervous systems, so we know there is no fundamental reason a more complex life form couldn't handle it.

Some kind of grasping and manipulative organ capable of delicate work would probably be predictable for a technological species, but it could be a tentacle, lip, trunk, tongue, who knows? Look at all the little labial parts insects have to manipulate their food, shape mud balls for nesting, build honeycombs, etc. Our own hands (and feet) originally evolved for grasping branches and picking fruit, not working flint or building spacecraft.

We can even speculate on more bizarre configurations. Maybe they parasitize, or domesticate and train other creatures and have them do all the manual work, while they ride along. After all, we use horses, camels, oxen, elephants and dogs in similar ways. Maybe they are sexually differentiated this way, one sex does the lifting and drawing, the other is in the driver's seat. (No snide comments, Jody!). There appear to be very good reasons for sexes, and also very good reasons for only two of them, but after that, anything goes.

One of Larry Niven's races is tri-sexual, with the third sex being of a different species altogether, like the digger wasp's prey, where the female lays her egg IN it so the hatched larva will have plenty of live meat to eat. The third sex has coevolved with the Puppeteers and they have further modified it for breeding purposes. It survives because they nurture and protect it. It is thoroughly domesticated and could not survive at all without their protection.

We can visualize hive species, with multiple castes, larva and pupal and adult (or even more) stages, or even alternating generations of totally different body plans. All these variations exist on earth, they could very well exist out there. And who knows what prosthetic appliances or genetic or surgical engineering could be employed by a truly advanced species.

Chances are they will be totally disgusting, and they'll probably feel the same way about us.

The real question is...will they be Communist or Capitalist? Or will they (shudder) have come up with some other alternative.