On older phones, Google Play Store hasn't still appeared in its current form, so owners of older devices need to use the former version of Google Play Store named Android Market to download new applications. According to the information which we gained today, this situation will soon change.
On the 30th of June Google plans to end their support for Android Market which still works on devices with Android in 2.1 or previous versions. If you are owner of device with Android Market on your smartphone, you shouldn't be disturbed because these smartphones will work normally. However, if you plan to use the newest applications or to be keep up to date with updates, you will need to purchase a new phone.