Breaking changes in SQL Server 2005

This particular change does not affect me, since I do not use Merge Replication. However it is very important to have your triggers prepared to handle multirow inserts/updates/deletes in any case (it does not matter whether you use replication or not). Extracted from http://msdn2.microsoft.com/en-us/library/ms143470.aspx regarding Breaking Changes for Merge Replication

Batching of changes In previous versions of SQL Server, changes made by the Merge Agent were performed on a row-by-row basis. In SQL Server 2005, changes are batched to improve performance; therefore, more than one row can be inserted, updated, or deleted within a single statement. If any published tables in the publication or subscription databases have triggers, ensure that the triggers can handle multi-row inserts, updates, and deletes. For more information, see Multirow Considerations for DML Triggers.

And here is the important info with examples (from SQL Server 2005 BOL, as usual) Multirow Considerations for DML Triggers