The next version of Windows Software Update Services - due out in the first half of 2007 (beta 2 later this year). It's goal is to become the best management solution for Windows and to really enhance the infrastructure. I recon they'll do just that - System Center Essentials 2007, System Center Configuration Manager 2007 and the next release of Small Business Server will all use WSUS. It's VERY good.
I've always been a bit of an SMS man (I can still remember the original 'Hermes' and have worked with all versions since) - I've played with SUS before and considered it OK (but not a patch on SMS), but WSUS 3.0 is something else. It's still not SMS, but it's close (and it's free); Obviously it does update management, but it will have support for a lot more than the basic Windows security updates - anything that's on Microsoft Update (including drivers & hotfixes). It will even be able to cope with 3rd Party updates.
It runs on a Windows 2003 server, needs SQL 2005, IIS 6.0 and the .Net framework 2.0. It's console runs in MMC 3.0 and can run on a management workstation. The console itself is far more functional than the current iteration - we've listened to the feedback and implemented all of it (views, columns, the ability to sort, etc - the default view only shows items that need action). It will run on 64-bit and is therefore about twice as fast. For high availability, you can use NLB at the front end and you can cluster the backend SQL database. There's finally going to me a MOM management pack (we're still looking for feedback on what should be in the management pack). Reporting uses SQL Reporting Services and can therefore be very granular. It's possible to rollup reports from all the servers or just from specific ones. There's a new Reporter's role - so you don't have to have access to the full power of WSUS just to look at reports. Reports can be saved out as Excel spreadsheets or PDFs.
Managed computers can be in more than one group and the groups can be nested. There are very granular auto-approval rules, so I could (for example) auto approve all critical updates for SQL to all the SQL servers in my test group. There's a neat little Server Cleanup Wizard, which will help you run a very lean server (no need to keep hold of a load of old stuff that you don't need anymore). We've even introduced a lightweight inventory - only around 30 hardware attributes (the basic stuff like memory, processor, disk, etc) and just software that's registered in Add/Remove programs.
Client support for Windows 2000 SP4 and above. There'll be an easy upgrade from WSUS 2.0 and it will be possible for a 2.0 server to sync from a 3.0 server (allowing an easy, top down upgrade).
That's all I can remember, but I was very impressed. Still think that SMS is the real answer, as it can do a whole lot more. But for something that's free....?