`#join` will call [`#to_s`](https://github.com/puppetlabs/beaker/blob/master/lib/beaker/host.rb#L115) on each object. That should do exactly what you want. If not you can also do (in 1.9.3) a:
```ruby
  a_host.map(&:name).join( ', ' )
```
in 1.8.7 you have to expand out the method deference:
```ruby
  a_host.map{|h| h.name}.join( ', ' )
```