I know nothing that anybody else doesn't. This is all pure speculation.
My skepticism about Xobni is:
1.) They're doing a lot of things that are commonly regarded as mistakes, i.e. launching too late, writing desktop software, making things complicated.
2.) A friend of mine did something very similar in 2003 - it was an Outlook plugin to categorize and organize your e-mail. He gave up on it because it seemed very difficult to get people to pay for an e-mail organizer unless it saves them the expense of having to hire someone to deal with e-mail, and it better be damn good if it's going to take over the job of a person. He perhaps didn't carry it through as far as he could've (he was coming off another failed startup and was running low on cash), but his observations seem valid.
3.) E-mail analytics seems to be an all-or-nothing product: either your software is reliable enough that you can just run it and trust it'll get the right answers, or it does more harm than good. If you have to double-check the program's results and/or approve every action, it'll cost you more time than it saves. I've heard that NLP has gotten much better recently, but I still had the impression that it's far from perfect. The Xobni founders and Gabor seem like sharp guys, but I kinda doubt that they're good enough to take what's basically bleeding-edge research and make it into something that business execs can just count on.
4.) They've taken a lot of money without users, revenues, or any proof that their market exists. As a result, they have, basically, one shot at this. If they blow it, they can't really flounder around until they find the right angle of attack; they're basically screwed.
I'm certainly willing to be proven wrong - really, I make these predictions so everyone can say "Don't you feel foolish now?" when I'm wrong. I learn better when it's humiliating. ;-)
But one thing I don't put much stock in is the "Well, lots of investors think it's good, so therefore it must be." Lots of investors is an idiot. (The subject/verb disagreement is intentional.) There've been cases - like Go, or the dot-com bubble - where everybody was certain that this was going to be the future, and it never ended up going anywhere.