Well, the title says it all:
What does the takeover of Nokia by Microsoft mean for the Ubuntu SDK, as the Ubuntu SDK relies on Qt which is (was?) a Nokia project?
Therefore, the takeover should have no impact at all on the Ubuntu SDK.
Furthermore, even if Microsoft did have any Qt copyrights or other assets--which does not appear to be the case--all released Qt code would still be licensed under the LGPL, and the rights conferred by the LGPL are not revocable by the copyright holder. So we could still use it, though it's possible they might choose a different license for future versions. Again, even this is probably not a concern as Microsoft doesn't own those copyrights.