Ruby has this great abstraction layer on top of Selenium called Capybara, which you can use do functional/acceptance/integration testing. It also has another library called Cuc
While the OP was happy with finding a Python Cucumber equivalent, what led me here was the question title: a Python equivalent of Capybara. While Cucumber uses Capybara, Cucumber itself is a whole different "solution" that is only incidentally related to Capybara.
If you're looking for something Capybara-like without having to deal with Cucumber, check out splinter. I don't know what was true when the question was posted, but Splinter is now built on Selenium, and supports other engines as well (Webkit, PhantomJS, zope.browsertest, and others), and supports both visual and headless testing.