Major news (even if it’s a day or so old), but the iPhone has 2 copy and paste apps now: Clippy and Clipboard. I have updated the reasons to jailbreak link adding this information. Check out a brief example of how it works using screenshots of me pasting from notes to safari using Clippy:

Here is the text, then mark the text.

Copy the marked text, then paste the text, in this case, I pasted into safari.

You can install Clippy from Cydia.

Clipboard shoudl be in Cydia in a day or two. See more information about it here.