I find Harold's post to be a bit confusing as it seems to contradict what the site says. But maybe I've misunderstood. I'm reading that they hold that money in some non-TFSA holding account off to the side and then on Jan 1 automatically place it into your official TFSA. If that's true then there should be no tax payable.
I disagree that the rates are low on TFSA accounts. If you compare the rates on many TFSA's to the so-called high interest savings accounts they are the same or very close. At the royal bank for instance, their high interest savings account and short term cashable GIC's all offer the same as what I can get in a more flexible TFSA that gives me near-instant access to my cash in case of emergency. Last time I checked, this rate was 1.25%, far more than that available in any of their regular accounts. When interest rates rise, so will the rates offered on TFSA's. I find them very competitive.
I also don't know what the actual ING bonus interest rate is. Since they are choosing to be cagey about it I am guaranteed not to invest my money there.