These "coronal mass ejections" will slam into the Earth's magnetic shield.
The biggest flares can disrupt technology, including power grids, communications systems and satellites.
"Our current view is that the effect of the solar flare is likely to
reach Earth later today (Thursday GMT), possibly tomorrow morning," said Alan Thomson, head of geomagnetism at the British Geological Survey
(BGS).
http://www.bbc.co.uk/news/science-environment-12493980
Andrew
The sky is falling! The Sky is falling!
We have been saved from dealing with IPv6 by solar flares! Everyone power off their computers and routers now. 
Jack (my bridge troll is very fat)
Huh, interesting how the media didn't panic.
Better references: http://www.spaceweather.com/
and http://www.swpc.noaa.gov/:
3-day Solar-Geophysical Forecast issued Feb 16 22:00 UTC
Solar Activity Forecast: Solar activity is expected to be moderate with a
chance for an isolated major flare for the next three days (17-19 February).
Region 1158 is expected to produce more M-class flares and still has the
potential for producing an M5 or greater x-ray event. There is a chance for
isolated M-class activity from Region 1161.
Geophysical Activity Forecast: The geomagnetic field is expected to be
predominately quiet on day one (February 17). An increase to unsettled to
active conditions, with a chance for minor storm periods is expected late on
day one into day two (18 February). The increased activity is forecast due to
the expected arrival of the CME associated with the X2 flare that occurred on
15/0156Z. Day three (19 February) is expected to be quiet to active as the
disturbance subsides.
*yawn*. "active" to "minor storm". Move along, nothing much to see
except some aurora.
Solar Activity Forecast: Solar activity is expected to be moderate
with
a chance for an isolated major flare for the next three days (17-19
February).
Region 1158 is expected to produce more M-class flares and still has
the potential for producing an M5 or greater x-ray event. There is a
chance for isolated M-class activity from Region 1161.
1158 is rotating away from facing directly to us so any flares at this
point will not be aimed directly at Earth as the earlier M and X class
flares were. Actually, I would be more worried if I earned my living in
orbit or at high altitude. 1161 is rotating into an Earth-facing
position but doesn't seem as active as 1158 was though that can change
tomorrow.