Yeah, most Ethernet connectors, now days, automatically detect whether they need a crossover, and will cross themselves over, if it's needed.
Even if your shield doesn't have this capability, (and the poster above me says it does), your laptop almost certainly does. And, as long as EITHER end of the cable has this "Auto MDI" capability, then your physical connection is good.
Now, if you're just using a crossover cable, then you do lose a lot of other functionality. Like, there's no DHCP server on your "network". (Unless you've installed software on your laptop to do this.) So both your shield and laptop will have to use manually assigned IP addresses. (And there's no DNS server, and so forth.)