Every so often, the AirPort connection on my Intel Mac mini would drop off for no apparent reason. Searching on the web reveals that I am not alone. This problem seems to affect the Intel Mac mini, MacBook, and MacBook Pro. While I am optimistic Apple will fix this problem eventually, I couldn't wait. So I wrote an AppleScript to test the network periodically and restart it when necessary.
You can read about (and download (4KB)) the script from my blog.
[robg adds: I haven't noticed this issue on my Intel Macs, but I have read of others having the issue. I have mirrored the script (but not the runnable version linked on the blog) on macosxhints, in case the first becomes unavailable.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060626224134955