I'm not feeling the love of Notes syncing either.
I'm using:
iCloud
iPhone 4S
iMac with Lion 10.7.2
MacBook Air with Lion 10.7.2
Looking in Mail (on both computers) and hitting Command+4 I see a note or two I typed several months ago. Was on Mobileme before, guessing that's how those notes arrived.
No new notes that I created starting last Friday with the iPhone 4S, Siri and iCloud. Notes syncing is switched on in System Preferences on all devices.
Hmmm. Would be nice if it synced. I've been finding that taking notes with Siri could help me on a daily basis, if it worked.
edit to add: signed in to iCloud.com and was able to view the same note that shows up on my computers. Can't add a note on iCloud.com (if you can, I can't figure it out)