The Democratic on-the-record and not-so-on-the-record responses (the Republicans were forced to put a lot of resources in the race, Bilbray underperformed Bush 2004, Busby's last-minute gaffe was costly and she wasn't such a great candidate, it's a very conservative district and Democrats will pick up our seats in Bluer quarters, look at how Busby performed with independents, etc…) are, trust us, not worth a warm bucket of anything.
Bottom line: Bilbray's victory shows that although Republican incumbents are running in a nasty national environment and although they are expected to lose some seats in November, the GOP is still favored to hold onto its majorities in both chambers because of several baked-in-the-cake advantages, including money, few retirements, safely-drawn seats, and a party apparatus that is adept at turning campaigns to local issues and turning out voters through micro targeting and hard work.