So, I finally watched this week's episode last night....
Since I am a Lost flunkie

, can someone tell me does this mean that Kate somehow ended up with Claire's baby?
The entire episode leads us to believe that she and Sawyer have a baby...and Kate even confirms that notion when she tells Jack to either man up or move on, in regard to "the baby"...to get over the fact that it's Sawyer's baby...then like always, they throw out a curve ball right there at the end...with the blonde haired boy (which very easily could be Sawyer's), but then she calls him Aaron (and they played that "Lost" somethings-gone-awry music).
I also thought that the reason why she smacks Sawyer and leaves him in a huff was because she was pregnant, and he rejected the idea of them having a baby...and she tells him that she isn't, because she didn't want to even bother with him from that point on...and she plans on staying on the island because she knows that she is wanted and is "high profile".
So, my theory now is that she really wasn't pregnant, and was turned off by Sawyer's rejection and is therefore "done" with him after that point. This leads her to decide to go back to the States...and something happens to Claire, leaving her with Aaron.
Unless she just happens to name her and Sawyer's baby Aaron as well, but that would be too weird.