Question: Just like the newly presented iMessage but instead of just between iOS devices, with the Mac too.

I've looked at Handoff. It can only send links to the iPhone from the Mac.

I've looked at Droplr. It requires public sharing on a Twitter account. Not what I want.

I've been using email and have been recommended Evernote. But these solutions require a document that I must create, wait to sync, and/or later delete to free up clutter. I just want to send a quick message.

I just want an app/application pair that can quickly share links, notes, and pictures between devices, like iMessage.

Does what I desire exist?

Answer: 
I agree iMessage is the best solution. For those that (for whatever reason, may not be able to use this) here is a solution for quick notes sync. I created a contact on my iPhone called "My Notes" and put what text I want on the notes section and it instantly syncs with Address Book on my mac. And at the desktop I do the reverse, I go to the same contact and add a note in the notes section and it syncs instantly.

Quick, no file to create/save/manually sync/whatever. 

However, it's only for quick text notes, not photos/files/etc.

I thought it was cool ;) but iMessenger is more complete and now it's available... but hey, it's good to have choices.
There is no need for third-party apps whether free or paid.

Notes on iOS syncs with Mail.app on OS X across accounts; iCloud not required. 

As far as pictures, they do require iCloud syncing. The photos part are synced to ~/Library/Application Support/iLifeAssetManagement/assets/sub each photo into a file. There exists a script that does copy the photos into a directory of your choice. You can search for it.

For movies I have not found a simple and elegant way to have them sync over the air yet; without the clutter of third-party solution of course.

I hope this does suffice.

It would be nice to click and hold on something you want to share in iOS and request that it be sent to OS X. Right click on something you want to be sent to iOS and have it sent that way as well.