I just found the following note the game's facebook page, it was published on December 11:

Details on the preorder:

• Preorder site will go live in the morning
• The game will cost $15 at launch, but will be available for a pre-order discount of 10%. So pre-orders will cost $13.50
• Pre-order 4-packs will be available for $45
• The pre-order is for the PC/Mac version only, not XBLA. If you are looking forward to the XBLA version, save your money!
• The PC and XBLA versions will launch at the same time
• The Mac version will likely not be available at the same time as the PC version, but will probably come shortly thereafter, however Mac beta testers have been running the game successfully in bootcamp, etc
• The pre-order will be sold through the Humble Store, and will come with Steam keys
• The Pre-order will NOT include beta access
• The Pre-order WILL include a bunch of goodies, to be announced soon

The game is already available for pre-order on the official website, but that bullet point made me want to wait for the next Humble Bundle. However, if you want to buy the four-pack - which gives you four digital copies of the game for the price of three - the official website seems to be the only place where you can do that right now.

I've also looked around and found no information regarding a release date for this forthcoming bundle. Actually I haven't found any mention of its existence outside of that facebook note, not even in the official twitter account (though they did retweet Monaco's pre-order announcement). By the way, since that bundle will include at least one awesome-looking game that hasn't even been released yet, I guess I'll get moderately excited for it.

This is pretty awesome news. Monaco looks fucking great. I'm stoked to play this game. STOKED I TELL YOU!

Yeah, it'll probably bee the above-average bonus game on some upcoming humble bundle. Hopefully it'll include the soundtrack too.

Aw man, my friends and I have been quite excited for this game for a while...it'll be fantastic if it's in the next bundle (since I'd rather get it through Humble Bundle than just preorder the game alone).

I don't think it is apart of the next Humble Bundle. They are just using the Humble Store to sell their game. At least that is my understanding. Also, if you pre-order the 4 pack you get the bonuses.

Yeah that sounds more like they're just using the store to deliver the game

Castle Story did the same thing as well as others I'm sure.

Humble Store is an ongoing beta of a project from the Humble team. Basically its a store front that delivers DRM free games, at whatever developers wish to charge, with an optional "Pay more if you want" deal.

It's built around being highly accessable to developers to give freebies out for pre-ordering, adding soundtracks, push updates, etc, and can offer a Steam code. All Humble Store purchases get pushed to your Humble account as well.

HOWEVER, the Humble Store does not always equal Humble Bundle. Quite a few from the Humble Store have made it into the bundle, but the store front has a lower standard than the Bundle, and a lot less legal paper work. MONACO is being brought to Mac, which is a step away from Linux, which would make it a surefire bet for a Bundle, but not for a while.