The official Twitter client for Windows Phone received a significantly large update today. Post the update, you will be able to check out new tweets right from your lockscreen (notifications). Also, users can now choose between a 'light' and 'dark' theme for the app. Also, version 3.0 of the app allows you to selectively toggle notifications for certain (important) accounts, as well as pin keyword searches to your Windows Phone homescreen (tile). Twitter has also added support for an additional 13 languages with the new update. The app update is applicable for both Windows Phone 7.5 and WP8, in case you were wondering.
Grab the updated app from the Windows Phone Store by following the link posted here.