The UAE main page is located at http://www.freiburg.linux.de/~uae/.
A stable version can be obtained from Brian's site.
For the historically interested, the old 0.6.9 WinUAE is still available here.
Currently, UAE does not really take advantage of a second CPU. The M68K emulation should run on one CPU and the rest of UAE on the other. Although synchronization issues will significantly degrade performance, the goal is to achieve at least a 15% performance gain over the current version when running on the same dual-CPU machine.
This feature provides transparent access to the host machine's TCP/IP stack through a standard bsdsocket.library that is created at boot time. It allows you to run most AmigaOS network applications without having a TCP/IP stack installed on the Amiga side. Consult the release notes for details. [available with WinUAE 0.8.6 R4]
If you have a reasonably fast machine (> 233 MHz), you are invited to beta test a possibly optimal sound output method. Further information on this and other changes is available here. [available with WinUAE 0.8.6 R4]
If you would like to see where in the world the Amiga was most popular, take a look at the access statistics.