I'd have to agree with the previous posts. SOME with less than 3.0 GPA's have gotten in but that is one very small number, and these people probably had post-bacc, and/or graduate GPA's to throw at the adcoms, not to mention some personal challenges like taking care of a family. Also these people tend to destroy the MCAT to offset the low GPA.
Now you have a few challenges here.
1) You need to bring the GPA, so post-bacc is the clear choice. However you might be ruled out of an official post bacc program, since most require a GPA of 2.7, and an 8 on each section of the MCAT. Thats the trend here in CA (UC's), however it may be different elsewhere. You can find a grad program that allows you to take upper division undergrad classes as electives, but you GPA may rule you out of that, and you will have to take the GRE. Although some programs may substitute MCAT for GRE, your MCAT may rule you out of that.
Perhaps the only route is to do an unofficial post-bacc program, where you pay per class, or attend a non-degree earning program. However these are expensive, and tend to tedious due to having last priority in picking classes.
2) Retake the MCAT. The average for people getting in nationally is about a 28, obviously higher is better, and most schools treat MCAT and GPA equally, so deficiency in one can hurt you the same way. The MCAT is beatable, one just has to know how to study for it, but I can't make any recommendations since each and everyone studies and takes tests in a different way. Reality is, retaking the MCAT will only improve your score by 1-2 points. But its not impossible to improve by 10-15 points either. I know a few of the non-trads that have done that, and I myself have done it.
As Sundarban1 said, DO NOT RETAKE the MCAT again until you are READY. Ready as in you are scoring well on practice tests from say the popular test services including the exams from AAMC. Of course under real exam conditions as well.
3) Retaking classes that you did poorly in is not a guarantee either if you are on the MD route. AMCAS will count BOTH grades, so the lower grade will still have an effect, while improvement in the class you retook is not as good as one would hope. This is because the adcoms will EXPECT you to have gotten an A. You have the advantage that others do not (those that got a B for example). Already taken the class, you are expected to get an A.
If you are going the DO route, retaking classes is better. They replace the crappy grade with the better one.
4) Now the real kicker is, as Sundarban1 pointed out, there is no real guarantee. GPA/MCAT scores get you into the application game. NOTHING MORE, NOTHING LESS. You will compete against people who had low grades because they worked all their lives, but then proved their academic worth by getting a 40 on their MCAT. One can say that they had "challenges" during undergrad and what not, but without proof, the adcoms could take it as a grain of salt. This is why it is so important to have high GPA's in post-bacc or grad school, and get a high MCAT to prove to them that you have the academic ability to excel in med school courses.
In all honesty, you will have to really think about this, since the first two years of med school consists of science classes. At the end of your second year, you will have to take the USMLE Step 1 exam which will test you on these concepts. It does not end, and only gets more challenging. Doing well in med school = getting a good residency.
Ask yourself, if you are to take a grad/med school course in say pharmacology/toxicology, or histology, would you get an A? A good foundation in ALL of the sciences that you had (and more) as an undergrad = success in med school classes. I took general pathology with the med students and I was amazed how it integrated physiology, general chemistry, cell biology, genetics, biochemistry, immunology, and god knows what else. My friends who did not have the strong background suffered greatly. Four of them failed the class.
