They gave parking spaces to various units - even our 1 + den came with one. But lockers were not pre-assigned.
It was all done by who emailed first indicating their interest after receiving the letter from the marketing person.
However it is important to note - if you are not yet in the building you received your mail right to your current address and got it the day it arrived - if you were already living in the Centro condo as we are, the letter went to a Canada Post distribution centre and you only get your mail when you drive over to pick it up - since we picked it up 3 days after it arrived apparently those 3 days were enough for them to completely sell out of lockers.
Even though we purchased in 2008, indicated interest in a locker in 2008 and offered to give a cheque in full in 2008 - someone who just bought a unit in spring 2011 would have received their letter at home, replied before we did and received a locker.
I want someone at Henderson to explain to me on what planet is that a way to do business?