Rogers OS Upgrade list stated that the Xperia Arc and Arc S was going to get Ice Cream Sandwich in September, it looks like Sony has put a wrench in that plan but in a good way. They've announced via their Official Canadian Facebook page the the ICS rollout to the Xperia Are and Arc S has started. Unfortunately, this isn't an OTA upgrade so you will need to update via Sony's PC COmpanion software.
Also mentioned in the post is the Xperia mini pro, Xperia pro, Xperia S and Xperia Ion were still on track for a September upgrade.
Source: Sony Canada Facebook Page