there will be 3 ratings: bullet, blitz, and standard
just like on other major chess servers :)
I think there are several different practices for naming chess speeds. The USCF has two categories: G/30 and longer is Standard, G/60 and shorter is Quick (anything between G/30 and G/60 may be rated as both). I believe the term "rapid" is used by FIDE. I don't recall the time controls, but Bill probably has it right.
On the original internet servers (FICS, ICC) anything less than G/3 minutes is lightning/bullet. This includes games with increment such as 1 minute + 2 seconds (increment). But 10 seconds + 5 seconds is considered blitz on those servers. Standard time controls on those servers start at G/15. This is actually quite fast compared to OTB chess.
In the end there's no set in stone definition of what different time controls are labelled, or what is rated together. In the end, the powers that be (in our case, the owners of chess.com) make a decision, draw some lines, and we all play by those rules as fair as we think they are or aren't.
I was reading about the live chess testing now ongoing, when this question came to my mind: how the rating system will work after live chess will became available?
Just one rating for both classical and live games or (which solution I would rather prefer) a new specific rating will be added for blitz games ?
And finally, if this is not yet decided, could we discuss the matter or maybe have a survey of this topic?