This feature will help in the construction of buildings from blocks.
http://udkc.info/index.php?title=Tutoria...r_Building

This feature will be really helpful.
http://www.youtube.com/watch?v=AlDWrhJyY2Q

This would be nice, but here's a workaround for right now if you don't know it already.

Turn off Heightmap Aligning, then select the block in the air and press insert to duplicate. The new block will be positioned in the air.

also there is positioning mode - enter coordinates using keyboard

Is there an X/Y snap to grid function perchance?

-Ash

While in Object mode (shortcut is 2), goto Object > Grid Aligning, or press Ctrl + G. The snapping size can be changed if need be by going to Object > Change Grid Size, or press Shift + G.

vertical grid aligning will be in next sdk

Cool.

Awesome, thank you.

Cool, thanks.