My 6.5 year old daughter (possible aspie IMO) talked precociously early. Actually it wasn't that "early" overall...she had a few words before age 1, but then she gained language very quickly and could speak in sentences very early. She still excels at speech, but I would say that she has a few minor difficulties with pragmatic speech...she is going to public school next year and I'm very interested to see what happens. She refuses to talk on the phone (even to people she knows very well), and has developed a slight stutter.
My 3.5 year old son (possible PDD-NOS IMO) has been speech delayed. He started therapy through EI at 18 months and had a couple of single words at that point. He stayed at that point for a while...at 2 years 5 months he had only gained a couple of words. Then he started to gain more, and by 2 years 8 months (ish) he started putting them together into 2 words phrases. He's now 3 years 10 months and is considered "age appropriate", though he still has some intelligibility issues and some of the late-developing sounds (L, R) are still muddy. But he uses long sentences and can carry on fairly good conversations.
I'm not sure whether either of my kids are truly on the spectrum or not as we haven't pursued diagnosis, but I'm relatively certain at this point that they both have at least a big toe on it. 