Both have proven beneficial for obvious reasons. Some notes...
A common misconception is that the Cell was a high-priced component of the PS3 during it's launchtime. That's not true at all. The RSX and the XDR RAM were both more expensive than the Cell by quite a margin. Ironically, these more expensive parts are responsible for the bulk of PS3's architecture bottleneck (very low RAM avaliable and dedicated shaders).
Second, the Blu-ray. That's a bit tricky and I'm not so sure on calling it beneficial. It is the main reason PS3 launch was delayed on Europe and it made the PS3 considerably more expensive (production cost up ~$250 from a normal DVD reader). In the other side, it helped to hold piracy at bay, offered a massive increase on storage size, and it triggered blu-ray's victory over HD-DVD.
