I haven't been around TomTom long enough to know the whole story. It would be interesting to hear from somebody who has, or who has gotten TomTom's official side of the story.
From what I can gather, they once offered a Software Development Kit (SDK), which provided interfaces into their system for use by third-party developers. Webazar and others used this to create some really nice applications. But then when TomTom moved to the V7 software, they did things that broke some of the interfaces. And they simultaneously announced that they would no longer support the SDK, leaving the developers and users stranded.
My impression of this is that it was extremely unethical conduct. I think that TomTom has made a mess of the entire rollout of the V7 software, V2 TomTom Home, and the changes to its hardware line. Badly planned, badly executed, and badly supported.