Yes, with 2 JavaScripts or 2 macros assigned to hotkeys for fast execution you can move current line up or down. Here is the macro for current line down:

InsertMode
ColumnModeOff
HexOff
Clipboard 9
SelectLine
Cut
Key DOWN ARROW
Paste
Key UP ARROW
ClearClipboard
Clipboard 0

The cursor is at start of the moved line after execution.

I really don't like text files where the last line has no line termination.

Here is the macro for Line Down which handles this situation also correct:

InsertMode
ColumnModeOff
HexOff
Key END
IfEof
"
"
Else
Clipboard 9
SelectLine
Cut
Key DOWN ARROW
Key END
IfEof
"
"
Else
Key HOME
IfColNumGt 1
Key HOME
EndIf
EndIf
Paste
ClearClipboard
Clipboard 0
EndIf
Key UP ARROW

And here is the macro for Line Up:

InsertMode
ColumnModeOff
HexOff
Clipboard 9
Key END
IfEof
"
"
Key UP ARROW
EndIf
SelectLine
Cut
Key UP ARROW
Paste
Key UP ARROW
ClearClipboard
Clipboard 0

Note: These macros will not work for Unicode or UTF-8 files because of a bug with IfEof in currently latest release v13.00a+2 of UE (and any previous version).

2007-11-02: The IfEof bug with Unicode files was fixed in UE v13.20.

2010-12-31: Inserted command Key UP ARROW in the macro for moving line up to set the cursor to start of just moved line to be able to use the macro immediately again.