They can't depend on them anymore because the developers can see the Xbox 360 has a huge success in the market and its now profitable to go multi platform.
But saying that there are developers that are and have given the 360 more support and more 3rd party exclusives.

The only way Sony can this gen get gamers to purchase their console is to show more 1st party games and justify that £300 price tag even though on a technical level is is great value for money as a games console compared to the 360 at present it needs to do and show more.

Well we've all pretty much known this for ages. With the 360's large install base and PS3's growing even more coupled with development costs rising through the roof it makes more sense from a business perspective to go multiplatform.

1st Party titles need to come with more quality than quantity and there are some great titles on the PS3 from Sony. They do though need to lower the PS3's cost soon, 'cos people won't wait forever.

Problem is Sony, you dont have any 3rd party non exclusives either, most Devs and taking there IP to the 360 first and in most cases leaving it there, some 3rd party exclusives wouldnt hurt, and as we can see in japan a lot of devs there choose to support the 360 for the western markets as thats where the money flows, FF13 is prime example of this, sony you need to lose the closed mindset that 3rd partys dont matter they do matter alot!!, unless your nintendo then you have 5million first party IP`s to fall back on.

Had this come from Nintendo,Sega, or even MS themselves ,it would be meaningless banter. But coming from a company who always had great 3rd part exclusives is just plain ironic. I guess Sony can at least *sigh* a breath of relief that this didn't happen to them 10 years ago. How times have changed for them and everyone else. But Sony's in-house gaming division never came up with any decent IP's...its always been their 2nd/3rd party titles. But then again...they can always buy someone off I guess.