Despite what people may think, Microsoft isn't always wrong. In this case end users were simply not paying attention. Some sites weren't paying attention either, saying that SP1 for Windows Vista Ultimate is delayed. In reality, this is exactly as originally planned.
When Microsoft announced Windows Vista SP1 RTM, they said that SP1 will release only in English, French, Spanish, German and Japanese in mid-March. The remaining languages will RTM in April.
That might explain why Vista Ultimate users, after installing SP1, are not able to see the language packs on Windows Update. Of course, you'd have to put two-and-two together.
Anyway, Microsoft wrote a blog post on this, to get angry users off their back about something they already told them.
Of course, this doesn't get Microsoft off the hook for all the other SP1 upgrade issues, like the requisite updates causing endless reboots. Or the fact that people still feel it's overpriced, even after their new pricing announcement.