4.5 Preview was released today. The download is at http://stylecop.codeplex.com/releases/view/62209
I recommend the use of Style Cop to all C# developers.
I quote the download page:
This release currently contains 89 bug fixes since the 4.4 RTW release and includes 4 new rules.
SA1125 - UseShorthandForNullableTypes
SA1411 - AttributeConstructorMustNotUseUnnecessaryParenthesis
SA1517 - CodeMustNotContainBlankLinesAtStartOfFile
SA1518 - CodeMustNotContainBlankLinesAtEndOfFile
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