Inserting 'large' amounts of data

I have a web application which allows users to upload a lot of phone
numbers. I need to store those numbers to a database. Usualy, one would
upload around 70k-100k of records, totaling around 2 MB in size.

I'm using tomcat as an application server, and JDBC to connect to pg8.3
database.

I will have around 20-50 concurent users in peek hours, and even that is
quite overestimated.

I could create the temporary file on the filesystem where database
cluster is located and then execute COPY mytable FROM
'/tmp/upload-data/uuidofsomesort.csv' WITH CSV', but the 'problem' is
that database server and tomcat reside on different physical machines.

What would one recommend as the best way to insert those data?

Mario