The good people over at Sony Ericsson were certainly busy yesterday announcing new handsets. They spread the news about a handful of new mobile phones, including additions to the popular Walkman line that are destined for release throughout the third quarter of this year.

One the best of the bunch is the W710 Walkman, which is being marketed as a fitness phone. Not only do you get your standard chat-with-your-friends and jam-to-the-tunes functionality in this sporty $300-ish clamshell, but they’ve added a motion sensor and fitness software to the package as well. The other Walkman phone (W850) combines 3G data speeds with a sleek sliding form factor and optional speakers.

The Z550 clamshell is one of the cheaper offerings, being priced south of $250, but you still get a decent set of features including a 1.3 megapixel camera, and a web browser. For a few more doubloons, you can upgrade to the Z710 flipping business phone, which ups the ante to a 2 megapixel camera.

Rounding out the five is the M608c, which is destined for the Chinese market, and will include touchscreen capabilities as well as Chinese character recognition.