One of the most excited types posts you'll see on the BPAL forums (BPAL.org) is discussion on CnS.
No, it's not a type of scent. It's not some delightful goody someone just smelled. It's quite simple, actually: it's notification that your order has been shipped!
The United States Postal Service is how you're going to get your package here in the States, and when the order is leaving The Lab an email is generate to tell you it's on the way. USPS calls this a Click-N-Ship, and so the acronym CnS was born.
The reason this is so exciting is that -- well, clearly you're only days away from having your nice sniffies. But also, since The Lab brews your concoctions especially for you after your order them, sometimes it can take a little while. Especially around Lunacy or new releases.
So, join in the fun and report your CnS receipt. There's a spot on the forum just for this, so you can gloat shout with glee!