Well, I just asked a similar question regarding the Groove model: http://forum.mikrotik.com/t/groove-and-usb/61427/1 
I don’t own one, I just had a look at some pictures like this ones:
http://www.air-stream.org.au/files/Groove5-InsideTop.jpg
http://www.air-stream.org.au/files/Groove6-InsideBottom.jpg
Considering its smaller size and compact design I doubt it has USB… but it would be way cool and ideal for a project I’m thinking about (instead of using the OmniTIK which is a bit bulky in this case).