Here's a short but (hopefully) useful hint ... when you select multiple messages in Apple's Mail.app (MacOS X 10.2) and click the Forward button, Mail will combine the messages into one new message. Entourage, on the contrary, will open two or more new messages (I tried this on OS 9 since I don't use it on OS X). This means you have to copy/paste to get the same result.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20021202060427214