Numerous reports from Germany -including this one, on the official FC Kaiserslautern website- would seem to indicate that the Seattle Sounders have 30-year-old midfielder Christian Tiffert. Tiffert currently serves as captain for Kaiserslautern, his club since 2010; previous stops include VfB Stuttgart, Red Bull Salzburg, and MSV Duisburg. Tiffert is a box-to-box midfielder known for his passing, vision, and set-piece delivery. If the signing is completed, he would presumably slide into the central midfield role currently filled by Brad Evans.
Though the Sounders have yet to officially confirm the signing, Tiffert's agent tweeted that the playmaker has signed and will be a Designated Player. If accurate, that raises an entirely new set of questions; with the Sounders already at the limit of three Designated Players, the most obvious assumption would be that one of Alvaro Fernandez, Mauro Rosales, or Fredy Montero is on the way out. That is not a certainty, however; the Sounders could have arranged a deal that would keep Tiffert below the DP threshold for the remainder of this season, giving them the ability to make a roster move or pay down the contract of one of their current DPs in the winter. It's also possible that the MLS rules allow for greater flexibility than is currently assumed, and a contract could be bought down or re-structured before the signing of Tiffert is made official.
In any case, there's likely still much more to come before the end of the day when the MLS international transfer window closes. After the relative quiet of last season's transfer deadline, the Sounders look poised to make significant changes. How well the move is received likely depends on the manner in which the signing is accommodated, but it seems unlikely that anyone will be able to accuse Seattle of sitting on their hands this time around.