Yeah yeah yeah. I got something like a dozen emails about this so here I am posting before I get any more.
The nice little video above shows Pastebud (which is not live yet) working to copy paste between Safari and Mail on the iPhone. How is it done? Just little javascript bookmarks and some backend web services.
Now while a lot of sites on the web seem to think this is god's gift to iPhone users we hate to break it to you. This technology is extremely old news. Instead of waiting eagerly for Pastebud to go live just use iCopy which already does what Pastebud will do and has been out for something like 9 months. edit: Oh look another tool is already around that does the same sort of thing -- iCursor.
Enjoy copy pasting between Safari and Email. I'll continue waiting for something a little more comprehensive