They do let people port their phones over, but only from Sprint and my t989 tmo Samsung Galaxy s2 isn't listed.
I've heard horror stories about Republic Wireless, so I'm thinking not. I'd rather stick to a more 'traditional' type of company, not some weird wifi/regular calling combo.
Could have sworn they let people bring a phone over. Sorry.
Doing a quick google search comes up with platinumtel... kind of a crappy deal though. Only the first 250MB a month are "high speed".
You could always sell your phone and go with RepublicWireless. $259 initial fee for the phone and whatnot, but then only $19/month for unlimited everything.