As always it comes down to budget.
Rode just came out with the VideoMic Pro which is aimed specifically at the DSLR market. First reports are positive within its "restrictions" and price point.
There are devices like the juicedLink DT454 designed for DSLR cameras, but at over $400 you may as well start building a double system (separate audio recorder), which, no matter the camera format, should be the goal anyway. The biggest argument for going double system is that
there is no way to monitor the audio being recorded by DSLR cameras; you could shoot all day and find upon file transfer that there was a faulty connection and none of the of the audio of an entire days shoot was recorded.
Once you get into a separate audio recorder units like the the Zoom H4n and the Tascam DR-100 are ultra-micro-budget compromises that have serious problems to overcome. Yes, they work fine for the occasional filmmaker, but for anyone hoping to do serious work a "serious" audio recorder like the Marantz PMD-661, Fostex FR-2, Tascam HD-P2 or the Edirol R-44 is a must.
Mic selection is another area where compromises will affect the final product.
And, as silly as it sounds, simple things like home made boom-poles and shock-mounts create their own problems. In fact, it's probably more important to have a nice boom-pole and shock-mount than the nice mics(s).
As always, my advice is to hire a professional production sound team or hook up with a production sound up-and-comer. If you want to own your own gear you need to define your budget and make informed decisions from there.
Sound is half of the experience.