SharePoint 2010 has many wonderful improvements over previous versions. One of which is a vastly improved Content Deployment mechanism and API.
If your application makes use of Event Receivers or Feature Receivers, these can, depending upon what they do, cause problems during a Content Deployment job. If you have code that you’d rather not execute when your event is triggered as a side effect of a Content Deployment job, you can use the SPImportContext object to find out if a job is running, and if so, to take alternative action.
Here’s an example on an ItemAdding Event Receiver (you’ll also need a using statement referring to the Microsoft.SharePoint.Deployment namespace)
If you miss this out this check in an Event Receiver or Feature Receiver, you might cause deadlocks or spurious List Items that you did not intend.