We set up a US account with TD Waterhouse in New Jersey this past March and have not experienced any problems. We earn interest on our deposits and can invest funds into different long or short term securities.
While the income would have to be reported by TD Waterhouse, Canada and the US have a tax treaty and it is a simple matter of reporting your US income on your Canadian tax return.
There are additional reporting requirements with various agencies for specific dollar amounts. I believe that the once $10,000 amount has now changed to $5,000, such that any transfers of funds $5,000 or over has to be reported to US authorities.
It is not so much of a tax issue any longer but a means of curtailing money laundering and financing of terrorist activities.
For the most part, the onus of reporting and all the peperwork lies with the banks and not the customers.
We have similar reporting requirements for the same reasons in Canada but we are still at the $10,000 minimum
Malcolm