Not for now, as far as i know. OBSD is now using Sharp's bootloader.
But I guess it should be possible to write create a uboot script for OBSD, because the kernel and the whole system (= the soul? ) actually live in the internal microdrive.
I am also looking forward to this too so that I can resume my experiement of the pdaX test builds, while using OBSD as the ultimate productivity system.