Author: aharvey
[Added to the original trac issue at 11.06am, Friday, 5th November 2010]

It seems like someone is working on this, as there are a bunch of sport icons in the same icon set as most of the other Mapnik icons, http://www.sjjb.co.uk/mapicons/contactsheet#sport

If you copy the png icons from that link to symbols, you can then add them into inc/layer-amenity-points.xml.inc as,

<Rule>

  &maxscale_zoom17;

  <Filter>[sport]='soccer'</Filter>

  <PointSymbolizer file="&symbols;/sport_soccer.glow.20.png" />

</Rule>

I choose the glow ones as the green on green blends into much without the glow, but I think this goes against the convention.

I don't think (though I haven't checked) mapnik can eligantly deal with both a PointSymbolizer sybol and a TextSymbolizer, as adding these sport icons means that if you have a way tagged as,
leisure=pitch
sport=soccer
name=Joe's Field

Then the name is no longer rendered. Ideally I suppose you would want the symbol above the name.

Author: Mateusz Konieczny
[Added to the original trac issue at 7.39pm, Monday, 28th July 2014]

People in individual tickets suggested rendering specific sports: climbing (#2761), swimming (#5029) and canoe (#1960)

Author: math1985
[Added to the original trac issue at 8.29pm, Tuesday, 5th August 2014]

This issue is now being discussed on Github: gravitystorm/openstreetmap-carto#844

Therefore, I will close the issue here.