It is a facebook application, so if you want to connect your RL identity with SL you can use it, if you don't want to its no big deal, don't use it. And it's not the issue of collecting your data from second life, its the other way around. If you are a facebook user you already use plenty of applications and this will be one of them.
If there's no way thanks but if there is one thanks to the one who can share that with me.