Read a great Mailplane review this week on freerksmit.com! Thought I would pass it along!
Mailplane Review on Freerksmit.com
Mailplane - the best of both worlds?
... Conclusion: I have grown quite fond of the app. To me it provides a nice crossover between having the benefits of a stand-alone mail application and being able to use all (most) of Gmail's awesome features. Mailplane is probably not for everyone, but if you are a big time Gmail user I definitely recommend it.