Sparrow have just created a teaser site for their email client which looks to be coming soon for the iPad.
Something bigger:sprw.me/ipad/Coming soon.
— SparrowMail (@sparrow) June 6, 2012
They've made a simple sign up page where you just bang your email in and will be notified when it does actually get released. If you've used Sparrow on your Mac or iPhone you'll know how good it is so it's worth signing up for if you have an iPad.