These are the Facebook rules around running a promotion.
i. Promotions on Facebook must be administered within Apps on Facebook.com, either on a Canvas Page or a Page App.
ii. Promotions on Facebook must include the following:
a. A complete release of Facebook by each entrant or participant.
b. Acknowledgment that the promotion is in no way sponsored, endorsed or administered by, or associated with, Facebook.
c. Disclosure that the participant is providing information to [disclose recipient(s) of information] and not to Facebook.
iii. You must not condition registration or entry upon the user taking any action using any Facebook features or functionality other than liking a Page, checking in to a Place, or connecting to your app. For example, you must not condition registration or entry upon the user liking a Wall post, or commenting or uploading a photo on a Wall.
iv. You must not use Facebook features or functionality as a promotion?s registration or entry mechanism. For example, the act of liking a Page or checking in to a Place cannot automatically register or enter a promotion participant.
v. You must not use Facebook features or functionality, such as the Like button, as a voting mechanism for a promotion.
vi. You must not notify winners through Facebook, such as through Facebook messages, chat, or posts on profiles (timelines) or Pages.
The netmums competition breaks every single rule. It's not run through an app, there are no accessible terms and conditions which state that Facebook is not liable for the competition, or that, by entering this competition you agree to not hold Facebook liable for anything and they use a Facebook mechanism (sharing) for entry. They must be planning to notify winners through Facebook, as they're not asking for names and emails.
Basically, it's a huge mess. All the share to win competitions are, you have no reasonable chance of winning, they're totally illegitimate and there is the chance of getting into trouble if Facebook get arsey and have a crackdown.
I do loads of Facebook promotions for companies. Companies who don't do it properly drive me up the wall.
gets off soapbox and shuffles away muttering