I'm not a Microsoft fanboy, I am just very well trained in their technologies. I have been developing using Microsoft products for many, many years. So I have been rather upset lately at all the hype of the iPhone. It lacks so many features that Windows Mobile has had for so long. I use a Blackjack II. Prior to that I used MS Pocket PCs and other Windows Mobile smartphones. I have written many applications over the years for these types of phones. But I haven't nor have I seen anyone else write an application as smooth and useful as Twikini.
I am very excited to use this app. Hopefully because of it's speed and ease of use, not to mention its extensive featureset it will convince iPhone users that Windows Mobile is one hell of a competitor.

Below are the features from the product's site. It is well worth the download and very, very! cost efficient. Priced how mobile apps should be.
Overview
Twikini offers a powerful and efficient way to use Twitter on your phone. It
conveniently updates your favorite feeds in the background, and leverages the
camera, GPS, media, touch screen, keyboard, graphics and storage capabilities of
your device.
Our goal is to make Twikini the best designed Twitter app for Windows devices
in the world.
Main Features
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FAST! Unlike other Twitter apps for Windows® Mobile, Twikini is
written entirely in native C++ code for maximum performance and the fastest load
time possible.
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Simple, uncluttered, and customizable user interface. Choose from a
variety of themes for the best reading experience. (Screenshot 1, Screenshot 2, Screenshot 3)
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Post tweets using a full screen editor. Optionally, set your location
(either manually, using GPS coordinates, or geocoding) along with your status
updates. (Screenshot)
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Send and receive Direct Messages.
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Twitpic integration to post photos with your status updates. Select
existing photos or click new ones from your device's camera. When reading
tweets, view Twitpics inline (without having to open a separate browser). (Screenshot)
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Read status updates just like browsing a web page. Quickly reply,
retweet, favorite, or email other people's tweets. (Screenshot 1, Screenshot 2)
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Windows Media Player integration. Automatically tweet the song and
artist you're listening to. See a realtime feed of other people using it on Twitter.
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URL shortening services including Bit.ly, TinyURL and Digg.
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Single download that is compatible with all Windows® Mobile
devices - both touch and non-touch.
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And lots more...