Excellent small keyboard by
PFU America, Inc. with sensible placement of the
CTRL key. New users will find the fn-escaped arrow keys most disconcerting to get used to (it takes a week). The HHKB has "diamond keys", which
xev reports being associated with keycodes 129 and 131. You can map the diamond keys to be "Hyper" modifiers under
X with something like
xmodmap << EOF
keycode 131 = Hyper_L
keycode 129 = Hyper_R
add mod4 = Hyper_R
add mod4 = Hyper_L
EOF
If this works for you then you can think about putting something similar in your
.xsession file.