you cannot, but the notes are part of the data that is backed up, so in case of a restore, the Notes will be again uploaded to your iPhone from iTunes, assuming you do NOT select backup right before the RESTORE.
Options:
1) Create a label/folder on gmail called NOTES and mail the notes to you. That is what I do and I keep the notes on gmail and even access them when I do not have the iPhone with me.
2) I am aware of some freeware that could allow you to sync up notes. search the forum.
Currently there is no "syncing" of the notes from the iPhone. iTunes creates a backup of the database file when you sync but nothing really visible on the computer side.
You can use the option of mailing the note to yourself as a way of viewing and saving the notes on your computer.
You can also create one or more special Contacts entries and use the notes field for those. Since Contacts sync back laptop, anything in the notes field will sync back as well.
I found MobileTextEdit (
http://code.google.com/p/mobiletextedit/ , which you can also find in the Installer).
This is just fine for me, since all I want is to edit a number of ASCII files.
Now I only need a way to sync those ASCII files back and forth between iPhone and MacBook
automatically.