Quoting from the ESA article on the Venus Express findings:

"The eight Russian landers of the 1970s and 1980s touched down away from the highlands and found only basalt-like rock beneath their landing pads. The new map shows that the rocks on the Phoebe and Alpha Regio plateaus are lighter in colour and look old compared to the majority of the planet. On Earth, such light-coloured rocks are usually granite and form continents."

And:

"Müller points out that the only way to know for sure whether the highland plateaus are continents is to send a lander there. Over time, Venus’ water has been lost to space, but there might still be volcanic activity. The infrared observations are very sensitive to temperature. But in all images they saw variations of only 3–20°C, instead of the kind of temperature difference they would expect from active lava flows."

Full article here:

http://www.esa.int/esaCP/SEMUQCLXOWF_index_0.html

When the Pioneer Venus Orbiter (PVO, aka Pioneer 12) arrived in late
1978 to become the first US probe to circle the planet and perform the
first (relatively crude) radar mapping from space of its hidden surface,
PVO detected an amount of sulfur dioxide in the thick atmosphere that
was in the process of decreasing. Sounds like at least a few of the
thousands of volcanoes on Venus were erupting to me, and I doubt they
have stopped.

I wonder if there is a way to use Venus' intense heat and air pressure
as a way to power a long-lived surface probe, rather than see it as an
obstacle? I am thinking of this method because of the usual reaction to
nuclear reactors being sent into space.

In the 1970s, the Soviets were even considering using the Venusian
winds as a way to power their vessels, with models of rovers looking
like they had windmills attached. Surface winds are relatively mild, but
also relatively strong with the 90 Earth atmosphere pressure. Higher up,
they are strong enough to whip the entire cloud system around the
planet in just four Earth days.

Hey, if Venus does have geological activity, maybe the landers can use
the native geothermal energy some day for power and to run their
cooling systems.