Audi have always offered an SE version of the A3. Prior to the 2009 model year this included quiet a number of 'goodies' like climate control, cruise, interior lighting and storage packs, auto-lights etc. This was always priced the same as the Sport, but with different goodies.
For the 2009 model year Audi decided that they needed something between the Standard and the SE/Sport in the pricing so they took out some of the goodies on the SE and reduced the price by around £600. When I bought my 2009 SE I added back most of the options that had been taken away and the price worked out about the same. In some ways it's quite good because you only pay for what you actually want.
The current SE spec includes: 16" alloys with 205/55 tyres, front fog lights, DIS, front centre arm rest and multi-function steering wheel and it costs £650 more than the Standard spec.
If anyone wants to know what was standard on any A3 model let me know because I hace copies of the Pricing and Specification Guides going back August 2003.