It was expected in May, but didn't quite make it. But Windows Phone 7 users will be pleased to here that Angry Birds has finally arrived for the Microsoft smartphone this very day.Why is it such a big deal? Simple - it's one of the biggest-selling apps on both the Apple app store and the Android Marketplace. The arrival on the Windows Phone 7 platform will boost the profile of the OS and just might bump up its userbase a little bit. Not that we're arguing that anyone will go out and buy one just because of Angry Birds. But if it does make it more appealing for gamers.Angry Birds has just landed in the US store, with a UK version expected pretty much at the same time – the US one went on sale a few hours ahead of the official release date/time. The game, said to be 'the last in Xbox’s Must Have Game series for Windows Phone' according to the Windows Team blog, is free to try and $2.99 to buy in the US, presumably with plenty more levels if you stump up the cash. The full 195 to be precise. Expect the UK version to follow a similar pricing policy – and you can also expect the sequels to follow hot on the heels on the first instalment.