Is there software that can monitor the temperature of the Intel-based MacBook or MacBook Pro?

Yes. A quick search on VersionTracker or MacUpdate will provide a long list of temperature monitoring applications and widgets. However, many of these do not support the Intel-based models.

The highest ranked temperature monitoring applications compatible with the Intel-based Macs are available from Marcel Bresink Software-Systeme, a German software developer. This developer offers two programs -- Temperature Monitor and Hardware Monitor -- each available as Dashboard widgets as well.

Temperature Monitor is free of charge and is described as:

An application to read out all accessible temperature sensors in Macintosh computers. The program can visualize the history graphs of the readings, display measured values in a large variety of fashions, or announce readings by speech output. It can also store and export values.

[It] is capable of processing the hardware calibration data Apple stores individually into each computer. So it displays the exact readings Mac OS X internally uses for cooling control, not just an "educated guess".

Hardware Monitor costs €7.00, but can be evaluated prior to purchase and impressively can:

Read out all accessible hardware sensors in Macintosh computers. Currently more than 100 different Macintosh hardware sensors and more than 200 hard drive temperature sensors are supported.

The program can visualize the history graphs of the readings, display measured values in a large variety of fashions, or announce readings by speech output. It can also store and export readings.

Hardware Monitor monitors everything from temperature to battery data, fan speed to voltage. If you want to know every detail about the operation of your Intel-based MacBook or MacBook Pro, Hardware Monitor aims to please.