The Official Facebook app for Windows Phone 7 has just seen an update to version 1.5, likely to address bugs such as issues with Facebook Places and address a recent issue with a corrupt token which was causing log-in problems for some users.
There is however a new rumour going round of actual push notifications for the app coming, courtesy of Matthijs Hoekstra, Dutch Developer Evangelist at Microsoft/Windows Phone 7 development.
He later however sent a partial retraction, saying "What i meant is that ‘an’ app is coming for that, not sure about the official facebook app". I am sure we shall see however.
Via WPCentral.com