Blogging servic

Hello from new (potential) user.
First of all, I have heard best thing about WP, but I don’t know is it capable to do what I need, and I need my own blogging service.
I run my portal (based on joomla!) and I want to allow my users to create blog, is that possible with WP?
Second question: Is there some kind of bridge for WP->Joomla! ?
Thanks for any help.