We've heard this plenty of times before. Heck, even Dave Dobbin, CEO of Mobilicity said it was going to happen at some point but now, we've got more evidence of it actually coming to reality. According to some documentation found over at the Bluetooth SIG, it appears the Samsung GT-i9020A has been registered which leads most to assume that "A" stands for AT&T. While that may be accurate let's not forget that also makes it applicable to each and every major GSM player in Canada. Such as Rogers, Bell, TELUS etc.
Given the history of Samsung devices being abbreviated by carrier letters in their naming; this seems reasonable. Not unexpected by any means but reasonable. The Google Nexus One made its rounds to carriers in every GSM flavor; it only makes sense this will eventually happen with the Samsung Nexus S as well. Be it in March or some other month, we won't be too shocked when it does arrive.