Certicom has ~130 ECC-related patents. You probably don't want to have to crawl through them all making sure that your code, or someone else's code that you're using, doesn't infringe (and won't be found to infringe by a not-necessarily-infallible jury if you get sued anyway).
[EDIT again: actually, ECC does have a claimed big benefit, namely not needing such long keys. But one might reasonably be worried by the possibility that an algorithmic breakthrough some day might suddenly make longer keys necessary...]
The reality is, you need to consult a cryptographer before you implement any public key system. RSA and vanilla DSA are also spectacularly easy to screw up.
Unusual environments need special treatment.
Where I know we do disagree: public key crypto is a threshold over which I would not be OK implementing a custom cryptosystem. If I need public key, it's GPG or nothing. I am terrified of public key crypto.