Appigo has a very fine task management application called "ToDo.app". I've used it for about two years. It allowed me to synchronize tasks to one of two cloud services: Toodledo and Remember the Milk.
About a year ago Toodledo introduced their own task management application, but Appigo's sync still worked on both RTM and Toodledo. Appigo also added a desktop sync app, though it's remained in 'beta'.
More recently RTM introduced their own iPhone app. On May 12th they turned off sync support for all their customers who used Appigo ToDo.app.
... Late Tuesday night, May 11, 2010, we (Appigo) were contacted by the folks at Remember The Milk via email in which they informed us they had disabled sync access for both Todo for iPad and Todo for iPhone. This service has been available in two of our apps previously (Todo and Todo Lite for iPhone). Todo for iPad was a natural extension and no sync code was changed to support Todo for iPad. We don't agree with their assessment, but including this service in Todo for iPad violated their developer agreement, which was only valid for Todo for iPhone...A recent ToDo.app update disables RTM support -- since it's no longer available.
There's nothing about this on the RTM web site. For that matter, it's very hard to find anything about this on Appigo's web site either! The release history page, for example, says nothing about this update.
I doubt RTM will be in business in six months.
As for Appigo, they're not handling this very well. They need a lot more material on their main web site pages about what's going on.
Toodledo, where I'm a paying customer, is the only party that's coming out of this looking good. I like their "data freedom" approach to managing customer information.