Media speculation has immediately suggested that Matthew Upson will be a target of City in January. It's possible that this will be the case and that other Premier League talents will be targeted in a continuation of the trend this past summer. That being said Hughes has a tremendous record in finding high quality players in Germany and I think this is the more logical choice in the transfer window.
One of the curious things about Mark Hughes and his dabbling in the Bundesliga is that he has picked up players who are not German. RSC is Paraguayan, de Jong is Dutch, Kompany is Belgian etc. I presume that's a coincidence and German players could also be in the frame.
Vincent Kompany and Nigel de Jong both came from Hamburg of course and it is there that I wouldn't mind seeing City grab at least one more player. I've not seen central defender Joris Mathijsen linked in any location, but it is the Dutchman that is first on my list.
The reasons are practical. At age 29 he is a main stay in the Dutch national team and would add a layer of experience to the City defense. Crucially he formed a successful central defending partnership with Kompany at Hamburg where the two defenders also had Nigel de Jong playing in front of them. As such there would be virtually no issues in Mathijsen and Kompany working well together from their first game. Mathijsen is also a left footed central defender and would be able to take the place of Lescott seamlessly.
There have been recent media reports linking Phillip Lahm of Bayern Munich with City. That makes a lot of sense in some ways, the most obvious is that the German international has the added benefit of being able to play both LB and RB. However I tend toward yet another Hamburg defender, this time Left Back Marcell Jansen. Whether Hamburg would be willing to sell both players is I think debatable, but the symmetry and chemistry of the four former Hamburg players is the quickest way I can think of to allow City to plug the holes in their defense without an extended learning period between the players.
A German international that I'd like the club to look at is Per Mertesacker of Werder Bremen. Another strong young and tall defender, he is 25 and 6'6 Jansen is 24 and 6'3, who would be an excellent investment buy for the club as the Bremen defender looks like the long term solution at international level for his country. Mats Humels of Dortmund and Benedikt Howedes of Schalke are young German international defenders both of who I feel the club should keep in their sights.
Throw in Juan Roman Riquelme as the creative midfielder that the club needs and that would be the four players I would look at for arrival January 1st. Mathijsen, Jansen, Mertesacker and Riquelme. City's squad would be complete and allow the club to reach the goals set by the Chairman.