No current laptop that I know of can rival that of a higher end hardware calibratible monitor (all Eizo CG models, some NEC 80 series, most NEC MultiSync 90 series and the new NEC PA241W). A correctly calibrated reference monitor in a stable viewing environment is ideal for final color corrections. However, many photographers only have the option of using a laptop in the field or traveling. The practical realities mandate that when viewing on a laptop you should still calibrate it. Calibration provides viewing stability and consistency over time, and the profile created provides interchange for the next step, whether its printing, transferring to a lab or just editing and archiving back at your studio.
Several good software packages exist, my favorite being ColorEyes Display Pro. X-Rite has several packages: an i1Display2 or i1Basic with i1Match, ColorMunki device and ColorMunki software. DataColor has the Spyder3 variants.
Standard advice.... when shopping for a laptop, get one with as good a screen as you can afford. And then calibrate it. It will definitely help.