We just added full support for SMS in Canada[0], have local voice-enabled numbers in the UK, many more European countries on the way[1] and international SMS in beta[2]. If we're not where you need us, most likely we're working hard to be there as soon as it's possible.
If you have a phone number you want to use to make calls from in a country we don't offer local numbers, you can verify it to use as a caller ID then call to any of our supported countries[3].
[0] http://www.twilio.com/CA/pricing [1] http://www.twilio.com/eu-beta-signup [2] http://www.twilio.com/faq/international [3] http://www.twilio.com/pricing/international-calling-rates