From the announcement:
LITKO offers THREE thicknesses of wargaming bases to our customers... all are plywood (not MDF) and all are laser-cut.
3mm: Most affordable, most common, and lets you pick up the figure by the base and not the figure's head. Save that awesome paintjob!
1.5mm: More expensive, but the thinner profile looks great for 15mm-scale figures and below. More difficult to pickup by the base.
0.8mm: Similar in expense to the 1.5mm. Impossible to pickup by the base edge, but offers a slim look that hides the base very well. The focus is on the figure, not what it is mounted on.