"Most notifications are not being sent via email or inbox at this time. LiveJournal administrators are aware of the problem, and are working to resolve this as quickly as possible." http://www.livejournal.com/support
Of course, there's no notice of how long they think it will take to resovle, and there are a bunch of open support requests in their tracking system about this. (I won't open one myself since it is a known problem) I'd also found LJ had published their "news" email yesterday but didn't see (perhaps I read over it?) any mention of the problem--of course, I didn't receive that email, so it was by chance I even saw the news update.
I'd also spent too much time trying to see if the problem was me. Being a geek, I try to troubleshoot things on my own before bothering support: checking notifications settings, checking my inbox and spam folders, etc, etc. all took place before discovering that the problem is LJ's. Well, hopefully the admins will get it fixed soon.
Otherwise, I hope everyone is having a good weekend!