First...

$ gem install knit

...then:

require 'knit'

For example:

{:aardvark=>{:soup=>2}}.knit({:aardvark=>{:beans=>:fluff}})

# => {:aardvark=>{:soup=>2, :beans=>:fluff}}

Do you have a better way? Objections even? Fork away!

The gem is available as open source under the terms of the MIT License.