I just semi-proved this to myself while playing with a simple K2 blackpoint process.
If I use the "SharePoint List Items" event to create an item on a SharePoint list, that has plain text fields, it works.
If I use the same data to create an item on a SharePoint list that has drop-down fields in it, it falls over. K2 reports the following in it's log...
"229648","2009-03-25 02:21:13","Debug","General","15","GeneralDebugMessage","ProcessInstance.HandleException","15 ServerEvent: Server was unable to process request. ---> Invalid data has been used to update the list item. The field you are trying to update may be read only. ---> Invalid data has been used to update the list item. The field you are trying to update may be read only.","","","vm-moss2007:C:Program FilesK2 blackpointHost ServerBin","229648","01aa3ca6ac674bb3b2e0db4bdeb81e05",""
Can it really be true that the SharePoint integration cannot populate list columns when they are based on drop-downs ?