I recently received an email from John Marshall pointing out that everyone was reporting sequential write performance on my ReadyBoost compatibility chart, whilst the official requirements were for random write performance.
I couldn’t get to the bottom of it on the web, so I emailed Matt Ayers at Microsoft, the Program Manager who’s in charge of the ReadyBoost feature. He explained that early beta versions of Vista measured sequential writes, but that the release version measures random writes. Everything has been updated in the release version apart from the EventLog entry.
Matt has filed a bug, so expect that to be fixed in future updates. Thanks for pointing that out John!