Should a Vonage customer switch now?  Packet8 and Sunrocket are two likely candidates.  Both are offering interesting international calling packages.  Another option could be cable operator voice. While living in the UK, we had a never used phone line from NTL that was bundled with digital cable (never used because the landlord required that we maintain service with BT – must have been a shareholder).  However, I don’t believe the cable operators (Comcast for me) are providing deeply discounted international rates like the VoIP startups.

For the time being I’m staying put.  Although there may be more incentive to switch since a new provider might support Brendon Wilson’s Click2Call Firefox extension.