Archos,
It wasn't Shell who introduced the 5k/1000 foot limitation but Aero after a number of near misses in the zone. They had talks with Bristow who also agreed to implement it. Since being introduced it has been widely ignored, especially by Aero who tend to go as soon as the NAF Tower is no longer imposing SVFR, with the long waits that entails for start clearance. This is understandable as the NAF Tower tends to still be giving the official visibility from international for ages after the visibility has improved.
SAS,
GPS approaches are done in many countries outside Europe now, from USA and Canada to Angola and Yemen. GPS approaches are supposed to be getting introduced into Nigeria with the help of IATA and some oil companies (Shell, XOM and ChevTex - Total and Agip were hanging back last I heard). There were some IATA surveyors out from Canada back in August doing surveys at some oil company bases and NAF and PH International. It's been talked about for a long time, and most of the operators have their unofficial totally unapproved GPS approaches to get in when the weather has suddenly turned bad when returning to base on a 'VMC' flight. Finally it seems that in 2008 it may actually happen.
Norwyreq,
This happens every year in Harmattan when the limits for special VFR at NAF only permit flight when visibility is 1500m or greater. Last January there were no flights out of NAF for around half the month.