There's a great solution that demonstrates how to copy HTML content via the UIPasteboard into Apple's Mail app here. This works up until iOS 4.2 but not with iOS 5.
In iOS 5 copying the string:
<h1><font color="red">Hello World</font></h1>
results in this output in the Mail app:
<html><head></head><body bgcolor="#FFFFFF"><h1><span class="Apple-style-span"
style="font-size: 17px; font-weight: normal;">Hello World</span></h1><div>
</div></body></html>
Any ideas how to get rid of that Apple-style-span thing and leave the HTML content as is?