Actually, more information is needed to help you decide what you need to buy. There are two very distinct techniques for shooting in low light or at night, depending on what subject and style of shooting you need it for. Nearly all cameras, new and old, P&S or DSLR, can do well with technique #1. Technique #2 requires a good lens choice and a camera adept at high ISO and with good autofocus in poor light.
For landscape shots, scenics, buildings, architecture, and any other still subject, low light photos are best taken with the lowest possible ISO, a tripod, and a long exposure. It will always yield the best quality, sharpness, detail, lowest noise, best color, and complete control over the ambiance and light of the scene. For this, you don't need an especially capable camera.
If, on the other hand, your low light photos are going to be of people, action, moving subjects, street candids, handheld, or any other situation where either the photographer or the subject involves motion that you do not want to blur...then you'll want to look at DSLRs that can shoot at high ISOs with very low noise and good detail retention, and pair that with a good, fast lens. Cameras which are all quite good with high ISO shooting that would be worth considering: Canon T2, Canon 7D, Canon 60D, Nikon D3100, Nikon D7000, Nikon D90, Sony A500/550, Sony A580, Sony A33/55, Sony NEX3/5, Pentax KX, and Pentax KR. As you'll note, prices vary widely, depending on what your budget is. You'd probably want to look at picking up some fast primes - new or used...you'll want lenses that can open up to F1.4 - F1.8 or so, and base the focal length on the types of subjects you intend to shoot. A faster zoom might also suffice, though you won't find zooms that can have as large an aperture as a dedicated prime.
Sony DSLR-A580 / Sony 18-250mm / Minolta 50mm F1.7 / Sigma 30mm F1.4 / Tamron 10-24mm / Tamron 150-600mm / Tamron 90mm F2.8 macro / Minolta 300mm F4 APO
Sony A6000 / 18-55mm F3.5-5.6 / 55-210mm F4-6.3 / 10-18mm F4 / 35mm F1.8 / 16mm F2.8 / via manual adapter, lots of Pentax K mount, Konica K/AR mount, and Leica M mount manual lenses