Earlier today we called attention to new changes being brought about with the release of Windows Phone SDK 7.1.1, the release supporting 'Tango' in all it's low-end/budget glory.
We also mentioned in that article that only 5% of apps wouldn't run in the new hardware configuration, which is down to the amount of memory they utilise whilst active. However looking over this msdn page we wanted to make it crystal clear to our community that in fact there is a limitation for our new friend the Lumia 610: it won't run Background Tasks.
Specifically, generic background tasks are not supported for devices with 256MB of memory. A perfect example would be the background task used to update the live tile and cache in our own app. These types of tasks are known to developers as Periodic tasks and Resource Intensive tasks (if you want to understand the difference I recommend reading this overview). The potentially good news is that some types of background task, such as the background Audio agent which is used for playing music or podcasts after the app has been de-activated, look to be supported still.
A question therefore which I put to our readers, is this the first sign of platform fragmentation? Can we still state that "you get the same great Windows Phone experience on any handset"? Or is this a reasonable omission for the sweeter price spot?
Update: A quick clarification as some of our commenters aren't too sure, this does not affect fast app switching (part of the multitasking functionality) and nor does it affect push notifications which generate live tiles or toast messages. I'd also like to state that if apps make use of Background tasks Microsoft have provided methods for developers to identify when a "mid-tier" device is being used before trying to enable the task, thus allowing users to continue using all other features of the app in question.
Update 2: Justin Angel argues (very well) that this is not mobile fragmentation, as technically developers will write code once which can then be run on any Windows Phone platform, although developers may still be required to test for these mid-tier devices and run functions of their apps in accordance. Instead Justin suggests that this classifies as 'device differentiation', in the same way as not having a gyroscope or front facing camera in your device.