I gave SQLite, or is that spatialite, support in QGIS a try tonight. Surprise – it just works out of the box it seems. I know it may have worked in previous version too, but only now I just got around to testing it.
I downloaded a sample spatialite db, downloaded the latest QGIS (1.5.0-2 for Snow Leopard) from Kyngchaos. Unzipped the spatialite db, added it as a layer datasource, choose the three layers that appeared in the list. Voila.
Then I edited the file, added a point and saved it. Just to be sure I removed the layer and re-added it and my new point was still there. Lots more fun ahead for this great little “single file” datasource. Bye bye shapefiles… someday.