AppleScript URL protocol support
Getting the home directory:
set theHomeDir to the POSIX path of home directory of (system info)
Getting and setting the clipboard:
set whatever to the clipboard set the clipboard to "whatever"
Encoding URLs Personally, I think you're best off just piping it through PHP:
do shell script "echo myurl | /usr/bin/php -r \"urlencode(fgets(STDIN));\""
Bu there's also some info on Apple's website.
How does ScriptEditor know which app is scriptable? By looking for the NSAppleScriptEnabled key in an application bundle's Info.plist