I reviewed the 1.0 version of this great free web service on the WinMo side of our site here. Now version 2.0 brings full syncing of your tasks between the web and your gadgets (including iPhone). The service is free, but iPhone client is $2.99. The tool is great for coordinating and sharing tasks in a team environment, as even members who only have a PC or a Windows Mobile phone can participate...
Gather tasks in one place and share them with your family, friends and colleagues
Free Web version - all tasks available everywhere at any time (www.task2gather.com)
Automatic sync with web server - you will never miss your todo
Organize tasks and subtasks
Assign filter and tags
Ability to collaborate with WM users
Discuss each task in the comments area
Task2Gather supports English, German, French, Italian, Japanese, and Russian. It is available for $2.99 at appstore.