True, Xobni is not really all that new - but the application has recently gone out of Beta into something a bit more useful. When it first came out, it was merely a very quick indexing system in a pleasant interface that made getting more details on your contacts easier.
While its now a full release, it is not necessarily much more feature rich, but it is much much faster and stable. Whereas previously you had to wait quite a while for Outlook to start up, it does not slow down Outlook anymore. The interface is smooth, and it is easy to use.
While the feature set has not necessarily improved much, there is still very much to like - perhaps the most useful feature is that its indexing is much, much faster than the built in search in Outlook. Finding emails is easy and fast. But the feature I enjoy the most is that it automatically aggregates information on your contacts - for example, if your contact mentions his or her cellphone number in one of her emails, the application can automatically add this to their contact info, even if it is not included in their outlook contact details. Their profiles for services like Facebook and Linked In. Very handy. No more manual searches for this type of information.
Another feature I enjoy is its networking column - if I am looking for "Ben" and I want to email him, and I know he is a friend of "Dave", I merely go to Dave's profile in Xobni, and Ben's details will be there in his network.
Conversations between you and a contact are also threaded, so you can have both your standard email inbox open and specific threads open on the right once you click on a certain person's email. This makes it very easy to quickly find a specific email - and its associated attachment. Speaking of attachments, it indexes all the attachments shared between you and the contact as well. So if someone contacts you to resend a specific attachment, you simply search for it in the "files exchanged" view.
About a year ago Bill Gates demoed this application at a conference, and with good reason. It really extends the usefulness of Outlook to a much better application. Microsoft wanted to buy Xobni last year, because, lets face it, it brings significant functionality to Outlook. But Xobni did not sell, seeing as they wanted to develop for other email platforms as well, something we should all commend. Here's hoping they bring out something similiar for Apple Mail soon...
Highly recommended (and if you tried it before, give it a go again, it is improved quite a bit)...
PS: Off course my previous post (Apple opens up to Microsoft / new iPhone Red(mond) edition) was a April Fools joke! Sorry if I got anyone worried.