I should think there'd be *some* of the vanished megafauna still, in the high latitudes. There might be some descendents adapted to a warmer climate, too.
It would be interesting to see how a larger number of plant eating species altered the Americas' plant cover.
edit: rather late, I remembered there's been a thread rather similar. I copied one part, I think posted by boredatwork:
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wolves, foxes, raccoons, octopi, gorrillas, ravens, rats, dolphins, orca, sea otters, river otters, beavers.
All seem to have one or more of social/pack behavior, tool use, learning ability, and adaptability.
Any one of them could be the source of a new sentient or semi-sentient species.
Sans humanity, it seems reasonable to presume that some of the human-extincted megafauna survives (the Mammoths, the giant sloth, the european and north american lions) and some other animals never evolve:
Modern cattle, modern dogs, chickens, modern pigs (vs wild boars), and horses are all creations of humanity.
Similarly wheat, corn, and rice - would not be around.
The climate would likely be colder and more variable (evidence seems to indicate that the discovery of agriculture and conversion of large swathes of natural terrain for farming use altered the climate in early and prehistory).
No humanity = no boats.
The implications of this are pretty huge - much more abundant fish, few or no 'alien' species issues, the lack of engineering efforts to maintain navigable channels means that many river deltas would be unrecognizable to us.
No humanity = no farming = no overgrazing of goats => no or much smaller sahara desert?
flatter terrain as well in many parts of the world. No humanity = no cities = no ruins to be covered over by dirt and form mounds.
much fewer 'shooting stars' a decent number of what we see as shooting stars are actually bit of flotsam and junk from various space programs burning up in the higher atmosphere as their orbits decay.
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