That would be Skype no?

I'd wait to see what Google is going to do. Although I don't think they'll be updating their app for Maemo/ Meego but you can buy a gizmo account on ebay:

http://cgi.ebay.com/Get-Your-FREE-Gi...item27b33ed4e5

Dunno bout the reputability of the seller but I've bought accounts off ebay for Google Voice waaay back when they only had referral invites a year ago.