Android versions in the wild
Google recently released figures on the version numbers of Android phones accessing the android market. It's just validating what mostly all developers already know. All 1.5+ versions are important to support and different screens are as important.
Users are very fast to let developers know this, though. Already 3 months before the OTA update of Android 2.2 for my Nexus One I got a message about not being able to find an application in the 2.2 market from a user. The error is common, a default manifest file that has limits on API versions. I couldn't have tested the application on a higher API level at the development time so the abscence in the untested OS was not really an error. However it shows how easy it is to get feedback from users to correct such errors.
I have also gotten feedback on enabling the 2.2 install device (SD card or phone memory) as well as automatically generated crash reports that are also new in android 2.2. Adding to that it is for an application exclusively for Sweden where no 2.2 device has even been sold as of yet (but of course imported in different shady ways).
The chart below shows how important it is to keep backwards-compatibility in your applications, just like for web development and old browsers. Luckily the android emulators are very good and theres a fully functioning image for each and every API level. There's also other developer emulator images circling around where you can test the functions missing in the default images, such as a paid-app enabled market.
Source: http://developer.android.com/resources/dashboard/platform-versions.html
Dissecting the 4G term
The term 4G has been around in the news alot in scandinavia for a rather long time now. Mostly because of the Teliasonera network in Stockholm and the fights about the new wireless networks in Oslo. But lately it has more been dominated by the american networks.
However, the term 4G is already splitting off more than even broadband was doing at the start of mainstream internet connections. For now it has several common meanings:
LTE
4G has been the marketing name of the scandinavian 3G LTE networks (3G Long Term Evolution) whereas it will only at best (and in theory) lead to an actual 4G network in the end. The standards are actually just that - named to be the evolution towards 4G and not 4G itself. However TeliaSonera decided it was better to market something as fourth generation compared to third generation long time evolution. Makes sense from that perspective, really. But one could ask himself if that should not be considered false advertising.
WiMax
In the US it's another provider - Nextel Sprint - branding the new WiMax wireless networks as 4G. This is an even further stretch from the truth as the technology used will not even in a best case scenario go towards what is really the 4G mobile network. It could very well live up to the same performance but is not the 3G route into 4G as 3G LTE actually is.
4th Generation device
Some people seem very confused with Iphone 3G(S) now that the Iphone 4G is at the door. The name comes from the same term as the wireless technology; third generation. But the Iphone is merely saying that it is the fourth generation of the iphone, even though the third generation of the iphone was unluckily the first one to get support for the third generation mobile networking.
The real definition of 4G falls way behind all of these meanings. Will the real 4G have to switch name to leave space for all the illusions, perhaps?