enigma1 - 1:47 pm on Jun 11, 2009 (gmt 0)

I don't think this will be cloaking. Anything that has to do with forms for instance should be restricted via session cookies. You don't want spiders to login, create accounts, checkout, adding products to the cart or performing searches.

A good approach will be to redirect spiders and those who block session cookies to a page with instructions what the site requires in order to access them.

The robots.txt is more of a guide. It does not guarantee spiders will not access a page. If for example someone posts a link to an external site for your customers account page a spider will access it. And it should be redirected to say the login or create account page.

Now if your site is structured properly there should be no problem because the forms will use a post method so spiders will never be able to process them. So for example a search box can be visible in every case but a search cannot be accepted as there is no link tag really (so spiders cannot submit it), plus the script validates the posted data for humans who may block the session cookies.