hey, nice!
the small smd arduino looks like this Atmega8 board:
I allready used them with arduino, worked like a charm (only the clockspeed is different, so I changed the bootloader).
I'm currently in the hassel to swap that f'ing small MLF Atmega chip because I burned one... it's quite smaller than the TQFP version allready is.
Also check out the littleUSB board on the same site. a super small micro-USB to serial adapter in DIL16 package!
That would be a nice "dock" for arduino. I'm allready using like this for my custom arduino based 8x8 matrix module. But so far I could'nt find a bluetooth module with the same footprint. 
That would be really nice! Only this similar small one:
http://www.promiserial.de/promiesd02_e.htm
Are you going "software USB"/HID (AVR USB) for future arduinos? Like some suggestion I found via make's electro blog.