This program can fix a "corrupt" SMS database on an iPhone, which always shows an unread message count of 1 (or possibly more). This issue seems to happen quite frequently with the "missed call" SMS notifications sent by Vodafone Italia and other operators. It seems present in all versions of the iPhone firmware released so far (2.2 is the latest, at the time of writing).

Since version 2.1.0, the program is also able to fix any non-zero unread SMS count, including the cases where it is negative.

A brief discussion about the issue can be found on the official Apple forum.