well, i imagine the text field is part of a form which when submitted calls a controller action. In this case you can get the value as part of the standard params hash passed by rails, pretty much simliar to the :id param that can be passed.
For ex
code in the view text_field_with_auto_complete :customer, :name
can be retreived in the controller by using the following syntax @cust = params[:customer] @cust_name = @cust["name"]
Regards, Bharat http://blog.publishedperspectives.com