I love BlackBerry Messenger. I use it all day to talk to family and friends. But not all my friends have a BlackBerry. Just not talking to those people seems simple (and logical) enough, but I can’t do that, so what do I do?

Enter WhatsApp, the most potentially useful, cross-platform, communication app I’ve seen yet (not counting native messaging apps). WhatsApp looks like an early BBM build (see picture at bottom) and is flat-out QUICK.

The app sends SMS messages via your data plan. Setting up the app involves linking the app to your phone number and then using the app to communicate with your buddies. You can set your “Status” with one of the preset options, or create your own. It also imports/opens/makes available your native Contacts app, so there’s no strange-Google-Voice method to getting to them.

There is one downside, however: both people have to have the app in order to use it. Although the app is $2.99 in App World and $0.99 in iTunes (no Android love yet) I only know two other people who have this app, and I really only talk to one of them (also the person who helped me test this app). Luckily, he carries his BB every day, so this app still isn’t that useful to me. If more people had it, I’m sure I’d use it. It’s not that hard on battery (really saying something on a 9550) and doesn’t leak memory either.

All in all, it’s a great idea, just not popular enough to make it an everyday app.

<