Blackberry is rolling out an update to BBM for Android and iOS that lets users search and find friends from their contacts. Previously, there wasn’t really a decent way to find other users. Now, it will read your contacts and let you know who is using the service.
Also, if your contacts haven’t yet experienced the wonders of BBM, you can send them a quick (and non-spammy) email or SMS message, inviting them to do so! So, for the few who are using BBM for Android, look for an update sometime this week.
Source: Inside Blackberry