I am an NP here in Ontario. There are more and more opportunities for NP's in Ontario. It all depends on what kind of NP you are talking about. The College of Nurses of Ontario (our board of nursing) only recognizes the FNP certification from the US. You will also have to write the RN(EC) RN Extended Class, exam. This can be tricky for some US NP's as the scope of practice here is different. ACNP's do not yet have to write an exam, but probably will have to within the next few years. ACNP's have a little more leeway as they practice completely under medical directives and so do not practice independently. The role is actually quite new here (10 years). There are currently about 600 Primary Care NP's in Ontario and 250 ACNP's.
You can find out lots more information at the College of Nurses website or the Nurse Practitioner Association of Ontario (NPAO) website www.npao.org