Extended support means that Microsoft is still releasing security patches for XP. It does not mean that they are still making software for it.
Anyway, this post is a bit of a rant. But it is just driving me nuts that Microsoft is not supporting the most used Operating system on the planet. They should wait until usage dies down (like they did with Windows 2000. It was at 8% when they dropped it from .net 3.0.)
Microsoft was only incorporated in 1982. This means that Windows XP was released a full third of a lifetime ago for Microsoft.
How many other companies do you see supporting products from that long ago? Do you see Ford actively hurting their sales of new cars by selling parts for 1967 vehicles? Do you see Apple supporting any of the Power-PC based machines they sold in 2001? Do you see Google still looking like this?
The long story short is that (in the judgement of WinDiv in Redmond) was that pushing Windows XP SP3 and IE8 to Windows XP was a tragic mistake that encouraged users to stick with XP rather than putting in place an upgrade strategy for business. This combined with relatively lack-lustre take-up of Vista has really pushed Microsoft back from being far-and-away the top technical company in 2004 to merely one of the top in 2012.
Consequently, and I can't emphasise this enough, Microsoft are actively trying to kill XP, just like they are trying to kill IE6. They see it as damaging their sales of newer PCs, and they actively encourage products, third-party vendors and businesses to drop support for it.
That is why .NET4.5 isn't coming to Windows XP. It's not for any technical reason - it's because Microsoft see supporting customers on Windows XP as actively undermining their profit margins through Windows 7 sales, and since Sinofsky's department are currently beating the pants off of DevDiv in sales, Sinofsky is winning in the board-room to get Visual Studio, .NET and other critical DevDiv technologies to move to being newest-two-platforms-only.
Like it or hate it, that's Microsoft's policy; and for those who don't like it, the sad fact is that even with a 10-year support, Microsoft supports its products for more than twice as long as the nearest competitor in the market; Apple, and nearly 10 years longer than the oft-cited-alternative, Linux.