The Staff of Parlathan is a free in game epic weapon that Bioware gave away this past summer during the convention season. Anyone who signed up for the Dragon Age newsletter was emailed a code to redeem for the in-game weapon. This worked for most of the fans, but there was a small glitch that prevented a few people from getting their free item. Bioware (Webmonkey Jeff) managed to identify the error and fix it.
So everyone who should have been granted a code previously, but did not get one, can now get a code. Not only that, since it is the holiday season, anyone who signs up for the Dragon Age newsletter over the holidays will also get the Staff of Parlathan.
Please go to this page if you wish to get Staff of Parlathan for Dragon Age 2.
If you previously did not get your code or if you are signing up for the first time, please click the CLICK HERE (in that page) link and register for the Dragon Age newsletter (yes, even if you have before). You will see the code appear in your profile (this is an entitlement) and will be able to redeem it to your profile. You will NOT be sent a code through email nor will you get a confirmation email.
Update: Chris Priestly has mentioned later (after the announcement), that there is no code. If the staff is appearing in your entitlement page, then you will get the option to download it when the game is released.