Hey CurlyZebra...not sure if you've already decided to cut or not, but thought I'd weigh in since I have pretty similar hair to yours (in appearance, anyway!). I have had my hair short for years now, around shoulder length and above and I love having it short! Nothing QUITE as short as the example in your OP, but I've been slowly but surely trimming my way to a similar length.
If you do decide on a bob, I don't think your hair will look like the pic you posted, but it will probably look super cute. The girl in the bob pic has really loose curls that do not look like 3B to me. To give you an idea, my 3B hair turns into loopy, springy coils when short and healthy.
I think a more realistic example might be something like one of these, depending on how you style, thickness of your hair, and how springy your hair gets when it loses length.
If you do decide to lose some length, I would definitely start off slow as others have suggested! Cut a little at a time because you might be surprised (if you're used to having long curls) at how much your curls will shrink up when there's less length weighing them down! When I trim my "bangs" I can lose up to an inch in length after I trim 1/2 inch...so cutting 1/2 inch really equals 1 1/2 inches of total length lost. That's sort of extreme because these are really short lengths of hair to begin with (nose/cheekbone length), but you get the idea.
Hope that helps. Good luck!
CG since 8/21/12
3B, Fine, Low-Med Density, Low Porosity, Normal Elasticity (I think...)
I love henna!
Poo: Shampoo Bar
Co-Wash: Yes to Cucumbers
LI: Innsersense Organic Beauty Sweet Spirit
Styler: Alba Botanica Strong Hold Gel
check out my blog for more info about my styling routine @ http://killthebananas.blogspot.com/