Something to watch: EasyWP is a one-file script that downloads and unzips latest WordPress build on your web server (so the average Joe doesn't have to download the archive, unzip on his computer, and then upload everything). The file is rather immature at the moment (using only fopen(), needing Zip PHP extension, these things) but will evolve. Eventually this kind of feature has to be integrated to WordPress, I'd say.
How To Make HTTP Requests with WordPress
Making HTTP requests in PHP is not difficult, and a variety of methods exists: using fopen(), using cURL extension, using file streams with fsockopen() and fwrite() for instance. The problem is: depending on server setup, this might or might not work on another server. The good new is: once again, WordPress has a no-brainer API that makes it dead easy…