It's only version 0.2, but I've tested it from my Nokia 3410 and it works ok, with a few niggles*. Anyway, it's available as freeware here (requires free registration), as my own ISP don't support the necessary MIME types to download onto your phone, and they refuse to set them up ("Customer service? We've heard of it!").
When I get my act together tomorrow, I'll put the source code on my own website and post a link here.
*Your post must be short (roughly less than 120 characters) and use as little punctuation as possible. The reason for this is that MIDP uses http1.1 and the only way to get it to post successfully to a http1.0 server is to keep the entire message body down to less than 255 bytes.
Also, and this could be specific to the 3410, the password/username storage requires you to have quite a lot of room on your phone. The free ram is shown next to the title (in bytes). If you have any other large midlets installed, you may find it "forgets" your details due to a failure to store them successfully. Hey, it's only v0.2!