I've also noticed this, I thought I was crazy.  Not sure of the solution at
the moment, no time to play with it, but just confirming the anecdote.  This
is also using xterm for me.

Dan W.

>   I've just upgraded my notebook to SL 4.4 (from 4.3) and it looks like
> there is some difference in keyboard or '[x|u]term' config.   Until SL 4.3,
> up from 4.0, I had no problem in using CLI as usual.   After the upgrade
> I noticed some weird behaviour.
> 
>   The first one was during a 'vi' edit when hitting backspace key I got
> those "^?^?^?" (roubouts) in place of the usual destructive backspace.  In
> '[x|u]term' prompt I got :
> 
> $ stty
> speed 38400 baud; line = 0;
> erase = ^H;
> -brkint -imaxbel