SLD styles are not applied correctly when the data comes from Postgis.
For instance, I may want to create an outline effect by drawing street centerlines in as an 8px wide grey line on top of a 10 px wide green line. With data from Postgis, only the style listed first in the SLD file is applied. See the attached SLD.
I have tested this using railroads in NYC, retrieving the same data in a shapefile and in Postgis. I have also tested using the tiger_road style (without modification, the railroads also have a NAME string) with identical results.
I believe that text labels have the same problem.