HTML5 WebSQL databases are currently available in Safari (including Mobile Safari), and the HTML5 FileAPI is implemented in Phonegap.
Unfortunately the WebSQL API wasn't prescriptive in a number of areas; there is no canonical method of furnishing your HTML5 offline app with a pre-populated SQL database.
It took me quite a while to figure out how to get this to work reliably - so here's the solution.
This example web page will run inside phonegap, and probably any other HTML5 browser that supports SQL and File.
What is it
A demonstration of how to pre-populate an HTML5 webSQL database using a textfile created by the sqlite .dump command.
Copy the index.html file into your phonegap app /www folder
Create your SQL seed file from a SQLite database using the command:
sqlite .dump <database_name> > dump.sql
If using phonegap, copy the dump file into your www folder.
Edit the SQL_DUMP_FILE global variable.
Compile and run.