There's no virus or trojan for the blackberry for now. There's no worry there. People may add you to BBM, you have to accept their request, and you can always delete them if you need.
__________________ The difference between stupidity and genius is that genius has its limits. When you take things for granted, the things you are granted, get taken. Even a mosquito doesn't get a pat on the back until it starts to work. Too many people miss the silver lining because they're expecting gold. [BES 5.0.3 / GroupWise 2012 HP2]