So, iOS 4 is out, but as its multitasking talents are dependant on app developers updating their existing software, this specific feature is only working, at present, on very few applications. And even fewer important ones.

As we foretold over a week ago, it may take a considerable amount of time before you will be able to multitask properly, among the apps you use more often. And, in some cases, never at all.

Indeed, a lot of the apps that we've seen updated since June 21 (iOS 4 launch day) still haven't got multitasking enabled, and are simply upgraded to be compatible with the operation system on the most basic of levels.

Thankfully, though, there are some keen publishers and developers that got their patched apps to Apple on time and these are the best that we've tested so far. There may be more out there, but we've actually tried each of these and can guarantee that they work.

Not many of the social networking sites have managed to get fast app switching into their clients, with Facebook even having an iOS 4 update without multitasking, and Windows Live Messenger launching this week without. LinkedIn, however, works well with the new feature.

The first of the big name games to feature multitasking, this tower defense game of strategy, forward thinking and the undead taking on fauna, pauses the action when you have to nip off to send a text, for example.

Updating your blog is now even simpler as you can nip over to another app, or change songs on iPod, without losing your place as you type. It's also been updated to be clearer on the iPhone 4's retina display.

One of the first apps to be updated on the Pocket-lint iPhones, this currency exchange calculator will now keep any information you have requested.

WIll remember exactly where you were, even when you zip from app to app. The cloud storage utility will also transfer files in the background.

The internet radio app of choice for the Pocket-lint boys. After update, it happily carries on playing in the background as you flit between apps.

Obviously for UK customers only, National Rail Enquiries is one of the best journey planner apps around (even though it's free if you use the online version). This is a major update, as being able to carry on with your train times search is imperative.

Coming across like the numbers round in Countdown and, er, that's it, Brainz is actually highly addictive - certainly, if you've got a leaning towards maths. It will continue where you left off when switched between apps. 

Being a portal to thousands of free audiobooks, it truly benefits from being able to continue to play audio files in the background as you work on something else.

The app of one of the most famous newspapers in the world now remembers where you were when you pause it.

The new app adds iOS 4 multitasking support as well as a stack of new features including updated maps, background navigation instructions, route sharing, departure reminder, eco routes and the ability to personalise your car symbol, just like with the stand-alone units. 

Obviously, there are several other apps that have introduced fast app switching, but these are the major ones for us so far. If you find any others, however, let us know in the comments below. It would be good to build a list of the ones that are compatible...