If that allegation is correct, it certainly worked on me. When I saw how much faster and smoother the iPhone 4's performed than my 3G, that's when I bought the 4.

I knew that my 3G used to perform as well as the 4 did, and that it was the software bloat making my phone increasingly sluggish. That irked me, but not enough to swear off Apple products.

The slowdowns were gradual enough over time (each release on the 3G got slower and slower) that I certainly suspected Apple of deliberately slowing down the OS to drive iPhone4 sales. But I only thought so in a joking consipiracy-theory kind of way. I never seriously believed they'd really do that.