Hooray! Ding Dong the witch is dead! Many SSIS developers have had to content with the expression length limitation of 4000 characters. This limitation has been removed in SQL Server 2012.
For ETL developers SQL 2008R2 (and earlier) this limitation will still need work arounds. This limitation typically rears its ugly head when dynamic SQL is required. It should be noted that the limitation applied to expressions and not the actual variables. I will be posting an article next week that provides a good work around for this issue.