This is a big deal for developers.

Device manufacturers such as Samsung and HTC like to add their own special sauce on top of Android to help differentiate themselves in the market. Unfortunately this means that they are somewhat slow to react when Google release a new code drop of the Android O/S.
Android Plaform Distribution

Android 1.5 12.0%
Android 1.6 17.5%
Android 2.1 41.7%
Android 2.2 28.7%

Data collected during two weeks ending on September 1, 2010

Other: 0.1% of devices running obsolete versions

These figures suggest that the device manufacturers now realise how important it is to provide a rapid upgrade path for their users when Google release feature packed updates like Froyo. This is important because when users can upgrade more quickly, fragmentation becomes less of an issue.