bb.rb

#!/usr/bin/env ruby

if remote = `git remote -v`.lines.find { |l| l.match /bitbucket/ }
  matches = remote.match /(?<domain>bitbucket.org).(?<path>.*)\.git/
  url = "https://#{matches[:domain]}/#{matches[:path]}"

  branch = `git symbolic-ref --short HEAD`.lines.first
  url += "/branch/#{branch}"

  system "open #{url}"
else
  puts "No BitBucket remote :("
end

Added support for remote URLs that use the SSH format. Modified to open current branch.