If you will recall, the official WordPress app for WP7 was updated to version 1.3 to support Mango, but was quickly pulled from the Marketplace due to a bug that the developers found.  WordPress has made its way to version 1.4, which has resolved the issue and still also sports the Mango support of its predecessor.  Along with fast-switching, the updated WordPress also has the following new features from 1.3:

"You can now share pictures directly from your photo album to a new post in the app, as well as pin your blog to the start screen for quick access."

You can download WordPress 1.4 here.  Happy blogging!