Now BBM can be used on an Android phone or iPhone.
There is a way to use BBM on a Windows laptop.

How?

Use the Android emulator on Windows PC :)

How?

Let me help you:
First, install the Java JDK: http://java.com/en/download/index.jsp
And install the Java SDK: http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
Then, the Android SDK: http://dl.google.com/android/installer_r20.0.1-windows.exe

Install them,
Open SDK Manager,
Choose your preferred Android OS, then the SDK will download it for you.
Open Adv Manager,
Click New, and name you device, so on.
Then, click Launch.

Now you have Android on your PC.

Next step: installing the APK
Just watch this video: https://www.youtube.com/watch?v=HVysAukOpCA

And here is the BBM APK: http://www.mediafire.com/download/bpkaeybi5c56enj/new+bbm.rar

Good Luck :P