All right, deep breath everyone.... First, things are always subject to change, and what happened yesterday, last night, or even an hour ago may not be 'current' anymore.
There is SOME metro and TGV service, but very limited, and very busy as you can expect.
Read here for an English language report, which is at least somewhat more hopeful than earlier in the week
http://afp.google.com/article/ALeqM5hE624h4tNUx06S-07MtvnXC15fhw
The best advice that I can give is that you consult the websites of the operators directly, as information
is subject to change!
For the metro system and RER trains -
www.ratp.fr
For the TGV and information about Thalys and Eurostar service -
www.sncf.fr
For the VEA shuttle (which is not impacted but may of course be very busy!) -
http://www.vea.fr/uk/index.asp I don't know if purchasing your ticket on line in advance guarantees you a seat, but expect the shuttles to be very busy and thus you may need to wait. You may want to consider a 'private' shuttle such as RS Transport/BS Transport instead
For taxis, a 'normal' fare would run you most likely close to 100 Euros, but with traffic snarled expect that to double at a guess. I would consider contacting a shuttle service now to confirm a booking if you are going from Paris to DLRP.
AGAIN, everything is subject to change and for those of you leaving in a few days, information released today may or may not help
There is reduced metro service - estimates are about 30%. But I checked 'my' line and there is one train every 30 minutes vs usual one train every 2-3 minutes. During peak hours, that train every 2-3 minutes is packed between certain stations, so you can imagine what it is like now.
For those sightseeing in Paris, plan on walking between major sights, or consider a hop on/hop off tour service. But remember, those will be much busier as well as tourists opt for that service in place of the bus/metro/RER system