I guess not. Looks like I missed those (They were added to blueprint on Wed Oct 29 2008).
I'll try to add them soon but I can tell you what they'll be now. You can add them to your project now and take them out later after the next release.
=prepend-top(!amount = 1.5em)
margin-top= !amount
=append-bottom(!amount = 1.5em)
margin-bottom= !amount
They're pretty dumb, IMO. But whatever floats your divs.
Chris