In the past they ran another round of rebates right before the summer (May/June), but, that also used to coincide with an early March release of the Ti/xxxD series. So they'd have that out for 2 months, then offer a rebate (or lens combo deal) and also have other lens deals.
The best deals are usually on the rebates that come in the early fall, and the ones going around this time (Jan/Feb). So, I wouldn't expect deals as good in June if they do another rebate program. Of course, that's all subject to change depending on how Canon wants to meet sales goals, etc