Officially, Microsoft claims that DirectAccess isn't a VPN, but for practical purposes that's exactly what it is. DirectAccess provides both VPN services and a way for network admins to push software updates and modify Group Policies to the laptop of a user who is thousands of miles away from your company's nearest IT staffer.
DirectAccess also gives network administrators the option to permit laptops to go directly to the Internet for most of the users' network needs while sending and receiving only office traffic through DirectAccess. With ordinary VPNs, once you're on the network, all of your traffic gets routed through the office, regardless of its actual content.
Another plus for DirectAccess is that, unlike with a VPN, you don't have to log in to it. Once you have DirectAccess set up, the connection is always on. With DirectAccess, you can't be caught out by Firesheep or other all-too-simple network snooping tools.
The other important feature in Windows 7 Enterprise Edition and Windows Server 2008 R2 is BranchCache. This capability puts a Windows 7 spin on the old networking cache idea of retaining a local copy of frequently accessed information. With BranchCache, if you and your coworkers look at the same corporate document frequently, the software will create a local copy and keep it in your branch's Server 2008 R2 Server.
Alternatively, if you don't have one of those, you can use Distributed Cache, an arrangement that involves directly caching the files on other local Windows 7 computers for distribution to other Windows 7 clients as needed.
When you look at the whole package, Windows 7 offers a lot of great networking features. Are they enough to persuade you switch OSs? Ultimately that's up to you, but for many businesses--especially ones that are moving their servers to Windows Server 2008 R2--the move is well worthwhile.