From the official PlayStation site:

It’s official – SCEA announced today the April 17 North American ship date for Gran Turismo 5 Prologue, available exclusively for PS3. Developed by famed Polyphony Digital, Gran Turismo 5 Prologue will be available for $39.99 on Blu-ray Disc (BD) and as a download via the PLAYSTATION Store.

The BD version will offer added value with an exclusive behind-the-scenes High Definition (HD) video feature called “Beyond the Apex”. This video will offer some awesome access to the folks at Polyphony and give some background on how they are able to create such a realistic and beautiful driving simulator.

So there you go all you GT5 officianados. Less than three months to go. Though I have to say that I think $40 is a bit steep for what is really a glorified demo.

PlayStation.Blog » Gran Turismo 5 Prologue Priced and Dated