I don't see any way to add channels - either a hardware one or a software one. You could use RSS but that is it. And I don't see any way to add an action. They could very easily add a "web hook" URL for a custom action.
I get really annoyed when I see sites like this that anoint winners. They already have an API to work with outside sites but they just don't publish it
Also, what's ifttt like to work for so far?
If you open it up so that j. random startup can announce "Hey, we provide trigger foo, trigger bar and action baz" in a way that doesn't require anything more than cursory human interaction on the IFTTT end of the transaction, you suddenly become the default aggregation point for new services...
And may I say that having to worry about spammy APIs is kind of an awesome problem to have.
It is much more important to get the experience right with one or two small specific cases first - and then to make it available to the larger public.