Update 13 March: The Tevatron experiments have just released new, stronger limits on the mass of the Higgs boson. Read about it here.
The first result, shown by both CDF and DØ experiments, is the observation of single top production. The top quark was first observed in 1995 by the same two experiments, but that observation was of top pair production (a top plus its antiparticle). This discovery was of single top quarks, with no antiparticle partner. In the Standard Model of particle physics, top pair production occurs roughly twice as often as single top production, and the top pair signal is also somewhat easier to see in data. The observation of single top production is important, because even though everyone expected the process to exist, demonstrating sensitivity to such a rare and difficult signal is an important milestone on the way to searches for even rarer processes, like production of a Higgs boson.
The other result is the most precise measurement (by a single experiment) to date of the W boson mass, by DØ. Whereas the single top measurement demonstrates increasing sensitivity to the Higgs, the W mass tells us what mass of Higgs boson we might expect. Since the mass of the W is supposed to come from the Higgs mechanism, a more precise measurement narrows the window of likely Higgs masses. The mass of the Higgs has interesting implications for current searches at the Tevatron and the upcoming searches at the LHC, because the Higgs may be more difficult to see depending on its mass.