Man, it’s been killing me not to talk about OWA 2010. Take a look at this screenshot:

First: this shot’s taken from Safari 4.0 beta 2 on the Mac. That’s right: OWA fully supports Safari on Mac OS X (not Windows) and Firefox on the Mac and Windows, along with IE 7+ on Windows. (I can’t remember if Linux Firefox is supported or not; I think so but I might be wrong). Safari and Firefox get the full premium OWA experience, with drag-and-drop, spell checking, notifications, and the rest.
Second: check out the presence jellybean in the upper-right corner. OWA is now integrated with OCS. In this case, the screenshot shows my mailbox hosted on Exchange Labs, which features Windows Live Messenger integration. Notice that my Messenger contact list appears in the lower-left side of the navigation bar, and that next to Arlene’s name in the message pane, you can see her presence jellybean. (Take a good look at the context menu on the jellybean, too– looks a lot like the one in Outlook, doesn’t it?)
Microsoft’s video showed conversation view very briefly, but this is one of my all-time favorite Exchange features. Here’s what it looks like in OWA 2010:

So, for the conversation titled “Introduction”, I can see all the messages in the thread, with the first non-deleted message automatically highlighted. The conversation view automatically includes deleted messages, sent items, and messages that I’ve filed in other folders, so I can get a sense of the conversation’s length and spread. The view in the message list (on the left) shows how the thread branches (not much, in this case) and the location of each message; the conversation view itself on the right shows the active message, along with controls to expand other messages. Of course, I can select, move, and delete messages either individually or as an entire conversation.
Now, some of you may be scoffing right now, saying “wait a minute– gmail has had conversation views for a long time.” That’s true. OWA’s view is richer; it displays more visual information and is easier to navigate than gmail’s current implementation. Take a look at these two screenshots to see what I’m talking about. The first shows a conversation originally imported from gmail as it appears in OWA 2010; the second shows it in gmail.

Speaking of gmail, OWA 2010 can aggregate and display in your inbox mail from multiple services, too. Check out what one of the Exchange Labs options pages looks like:

There are quite a few things to look at here. First, notice the account information pane, which allows users to set their own address, phone numbers, and so on. As an Exchange admin, I can control whether users may do so or not, but letting them do so has some obvious cost and time savings benefits for the IT staff. Second, apropos of self-service, check out the “Shortcuts” area on the right side of the screen: users can quickly get access to do a number of things directly from within OWA, like setting up Direct Push or creating server-side rules. Finally, notice the “Other Accounts” section; I’ve set up a link with my gmail account so that mail sent to my gmail address shows up in my Exchange Labs inbox. (OWA 2010 also lets you select the address from which mail is sent, much as Entourage does on the Mac, so I can send messages that appear to be from my domain or from gmail).
I could go on with features. For example, the message list isn’t paged any longer– it scrolls from beginning to end, just like Entourage or Outlook, seamlessly loading messages when necessary. There are tons of other little grace notes like this, but you’ll have to wait for RTM to see some of them!