First let me say that I am an iPhone user, but I have recently been asked how to update a Fan Page from the Blackberry.
Is there an application for that?
Of course a quick search on the Internet provided the expected results of the general public outcry for an application that quickly and easily let a person update a Facebook Fan Page, but alas there is no such critter.
In an attempt to at least provide options below you will find two different ways to solve your problem until an application is developed.
1. You can use your browser and go to m.facebook.com, this is the mobile side of facebook so it is easier to load on a mobile device. Once on facebook you can navigate to your fan page and update it.
-or-
2. Use an application like BlackPing. First you will need to set up a Ping.fm account and set it up to interface with facebook (and whatever other social media sites you are using). Once you have an account each time you use the BlackPing application, it will post out to all the sites you have set up. The biggest downside to this type of solution is that it will always post to your personal page as well as you fan page. If you are OK with family and friends seeing the messages you post for business, this would be the best solution for you.
There are options, all be it not the perfect solution, but you can at least be mobile with your Facebook updates, and I am sure that there will be an application that incorporates Facebook Fan Page updates in the near future.