I only do this when I'm asking the type of question that's liable to get answered by people who haven't actually read the question or the tags.
For example, I asked "Is SQL Server DRI slow?" and actually got a very good answer, but I suspect that if I hadn't added the "SQL Server" part then a bunch of people might have given irrelevant answers for other DBMSes (and the specific DBMS was the issue there). If I had just asked "Is DRI slow?" then the title would have suggested a product-agnostic question; aside from including the product name, there was no way to reword it to be more specific.
On the other hand, I also asked about "Approaches for generic, compile-time safe lazy-load methods", and even though the verbiage does not suggest a specific language, I think it's obvious to any reader that the language matters.
Honestly, it can't hurt to include the product name, but as dmckee says, just don't make it a "pseudo-tag" at the beginning of the question; make your title a coherent sentence that includes the product name in its proper place (i.e. "Is there an XYZ library available for .NET?").