Yes.

(It's a "world iPad" for both the AT&T and Verizon model.)

Whether a device functions worldwide for a specific wireless standard depends on the frequency bands that it supports.

E.g. The new iPad supports LTE, but only the frequency bands 700 MHz and 2100 MHz which are not used outside the US.

The iPhone 4S has been called a world phone, because it supports all the frequency band used for GSM worldwide:

• 850, 900, 1800, 1900 MHz

The new iPad supports the same GSM frequency bands for both the AT&T and Verizon model. Therefore it's a "world iPad".

Of course you need a SIM-tray, to make use of this. Like the iPhone, the iPad has a Micro-SIM card tray.

If you bought the device without a contract, it's unlocked!

The information about AT&T and Verizon is important when talking about LTE availability in the US. Only AT&T and Verizon provide LTE networks in the US that work with the iPad.

4G LTE is supported only on AT&T and Verizon networks in the U.S. and on Bell, Rogers, and Telus networks in Canada. footnote no.3 - iPad specs

This is important to note as LTE frequency bands used in Europe, Australia and probably most of Asia are not supported by the iPad. You will use DC-HSDPA, HSPA+ or UMTS instead for fast internet access.