Actually, you can use the last icon from the 2nd row to transpose what you copied.
You also can use Ctrl+Alt+V to open the Paste Special dialog box.
Another (longer?) way: ALT, H, V, T
The last method will do the following:
ALT start navigating
H open the Home menu
V open the Paste item
T choose the Transpose option
I use Excel in Portuguese, which have another shortcut key (ALT,C,V,T).
Can anyone confirm if I haven't messed up with any key?