For those who have been looking to get a PS3 preorder in today is the day. GameStop and EB Games stores in the US are officially taking preorders. A $100 deposit is required and is payable via cash, credit card or trade-in. Most stores are expecting to have maybe 8 units available with some select stores (translation: major markets like New York City) possibly getting up to 16 units. Preorders are limited to one per household (so much for ordering that 2nd unit to ebay off) and employee purchases are limited to 2 per store.
There's no guarantee that preordering will net you that system on launch day due to the limited number of units but it does make the odds that much better. Those wanting to preorder online via the EB or GameStop web sites will have a bit longer wait- they will be announcing online preorder plans once software and accessory availability dates are confirmed.
Now, if you'll excuse me, I've got a phone call to make!
Update- As quickly as it began it is ended. GameStop and EB have posted on their sites that preordering for the PS3 is done and no further orders will be taken. Information on preorders in Canadian stores and online will be posted when available.