http://grammartips.homestead.com/imply.html
Hi dannyk- I was always taught that the two were not synonymous. The distinction is explained in this way:
The best way to remember the difference between these two words is to think in terms of the model used by communications theorists. Communication consists of a message, a sender, and a receiver. The sender can imply, but the receiver can only infer. The error that usually occurs is that the word infer is mistakenly used for imply.
But i agree that it is more common now to see the words treated as synonymous