As pointed out by Dr. Wukoschitz, the German OLG Köln (02.07.2010, 6 U 48/10, AdWords-Markenbeschwerde, MIR 2010, Dok. 118) quite recently has found that the use of the TM-complaint with Google may constitute an act of unfair competition under (‘gezielte Behinderung‘ according to § 4 Z 10 dUWG) German Law if as a consequence, resellers of the TM-products are hindered from advertising for them. The consequence of a TM-complaint is that parties other than the TM-owner are not allowed to book the keyword for their ads.
The court argued that it was not enough that the reseller was shown only inside the search results, but stated that the choice which form of advertising to chose should rests with the reseller. Limiting the reseller’s choice through an ad-complaint was thus seen as an act of unfair competition.
As I’ve just learnt, Links&Law will soon report about this case in more detail!
Austrotrabant's Blog 
I agree it.