Read It All Here
Short skinny version: yes, LJ was bought by Six Apart, and no, nothing is changing for the worse. We're not going "paid-only", your permanent account will continue to be honoured, and things will progress nicely. Brad will make some money for this, and stay on to keep the place real, things should get a little smoother and prettier, and the TOS will be a little reworded (and you'll have to agree to it again; legalities and all).
This isn't the first time LJ has had an offer placed on it, far from it. But it IS the first time that Brad felt that the company doing the buying had the right attitude towards LJ and "got it". See, he's looking out for you.
Now, relax, have a drink, and get back to your regularly scheduled life.