Actually, there has been speciation observed in fruit flies in the wild. Someone just posted the article on this thread or another one rather recently.
Shubi, I think where those who have faith in evolution and those who don't part ways is in the area of limits. Evolutionists see no limits while its critics do. Evoutionists assume that the wide variation we see within kind means there exists an unlimited capacity for variation. Perhaps there is, but there's no evidence for such a claim.
What is the age of the oldest person who ever lived in modern recordable history? I'm too lazy to look it up, but let's say it's 121 years, 5 months, sixteen days. Okay, there appears to be approximately a 120 year upper limit on a human life. Does that mean no one ever crosses it? No, they might cross it a little. And someday the record might be broken. But does it follow from that that we can expect people to one day live to be 13,672 years old? Perhaps we might freeze them and that can be obtained. I don't know. But does anything in the realm of nature lead us to believe such ages could be obtained, or could have ever occurred by natural processes?
An evolutionist looks at a Great Dane and says, "Wow! If breeding can lead to a dog that large, who's to say millions of years of random accumlated mutations couldn't make it 20 times as large?" They assume that because there's variation within kind, there's no limit to variation, even without man's help.
I think that's a rather wishful assumption. Yes, speciation occurs. The genetic capacity for limited variation that exists in each species allows for wide divergence due to either deliberate breeding or random isolation of some species members from others. On the extreme edges of this variation, it may be possible that mating no longer can occur with certain other species members either because of the obvious physical impossibility (Great Danes & Chihuahuas for example) or because of loss of the genetic capacity.
But there is nothing to lead anyone to believe that this is anything other than an outer limit being reached. To simply assume that from the extremes within each species, there will then occur random mutations which can carry the creature in question not only beyond the observable limit but into radically different genetic territory is just wishful thinking. Unless that happens, there can be no evolution, and since we can't tolarate that possibility, we must assume that over time those micro-organisms that somehow managed to appear all those eons ago "evolved" into all the millions of life forms we see today.
Can it be proven that that didn't happen? Nope. Can it be proven that it did? Nope.
So there we are. Choose your faith.