Pal Jim Courtney has penned a very good round up piece about Skype on the Go, and had it posted on GigaOm as one of the guest blog postings that have been appearing there in Om Malik's absence.
As someone who has been using the 3 Skype phone, I can tell you it is a very different experience having real presence when mobile. It makes the "free" calling also very valuable. When I'm in the UK I find myself in cabs or in cafes, and no longer needed my laptop to be open, yet I can find the people I need to talk to, and have pretty much eliminated any kind of telephone tag. That in itself is a reason to have one if you're in a country where it works.