Sureshot
What sponsors
Consoles have an incredibly high research and development cost (similar to the R&D cost required to produce a new car, the figure in USD has 8 or 9 zeroes). Moreover, the cost to produce a console is much higher than its selling price. So when the PS3 hit the shelves, Sony will have probably spent more than a billion dollars and earned nothing yet.
To boost the first sales :
1) the release date will be delayed so that people will be eager to buy it, but not enough to miss the Christmas period
2) the shortage will be organized to make people rush to buy it without thinking twice
3) some highly expected games will be released at the same time to fuel the sales.
But there again, these games will cost a few million dollars each to develop, and will only be sold $50 or $60.
So how can Sony make money in the end ?
Well, first they need to sell quickly as many consoles as possible to secure the biggest market share : that'll ensure profits on the long term.
Then they need to schedule exclusive games (that won't exist on the X-box or the Nintendo) on a regular basis to fuel the hardware (console) sales.
Finally, they will have to rely on several independant studios (Konami, EA...) to develop a lot of games. Sony doesn't need to invest money in these games but will earn money (royalties) instead. And that'll ensure the short term profits.
There is absolutely no sponsoring involved in it.