Sparrow for iPhone just received a nice update that marks several items off users' wish lists. Among that is the ability to compose in landscape mode, create/edit labels and swipe between messages, plus additional localization. Sparrow now is available in English, French, German, Spanish, Italian, Japanese, Dutch, Russian and Chinese.
However, the developers announced on Sparrow's blog that they were unable to get VoIP privilege from Apple for push notifications. Sparrow will have push introduced in a future update, but it will be done on Sparrow's side, and the company will charge an annual subscription.
Sparrow for iPhone is US$2.99 in the App Store.