No, that's not a typo. In conjunction with the rolling out .NET 3.5 SP 1 to Windows Update, Microsoft is planning a "service release" to fix some of the bugs introduced by SP1. According to Jon Langdon of Microsoft,
Additionally we intend to include this fix in an upcoming servicing release, a roll-up of sorts, which will be released in synch with 3.5SP1 via Windows Update. I.e. when 3.5SP1 starts getting pushed out broadly, so will this fix. We’re still working out the exact timeframe for this release but our hope is before the end of the year.
Of the six open issues we reported in August, only the one on serialization and the one on reflection were corrected. Doubtless other hotfixes will also be included once the formal announcement is made. For more information on why these and other issues happened in the first place I direct you to Scott Hanselman's write-up.
