A serious drawback to the command-line osascript tool is that it doesn't provide a way to pass arguments to a script. A workaround is to use the clipboard to store data (via pbcopy), then retrieve it from AppleScript's the clipboard object. For example:
echo 'Test text' | pbcopy; osascript -e 'tell application
"Finder"' -e 'activate' -e 'set theMessage to the clipboard'
-e 'display dialog theMessage buttons "OK" default button 1'
-e 'end tell'
The above is one long line; replace each line break with a single space when copying and pasting. You can substitute any command (or series of piped commands) for echo 'Test text'.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2003111916263473