I have exchanged a couple of e-mails with the hiring manager at one of the internships I was interested in. Basically, he said that he would be pleased to have me in his group over the summer and gave me a choice of two projects. The same day (Feb 27), I got an e-mail from Martina Ludwig saying that DAAD has recommended me to the same internship and that they have asked the company for final approval by Mar 5 (i.e. today), after which they will send me an official confirmation.
I am optimistic, but still waiting for an official notification.