A 737-800 pushes back from the gate at Dallas Love Field. Source: Southwest Airlines.

If there's an identifying trait of the legacy carriers -- other than globe-spanning routes, of course -- it's extra services meant to attract and win business customers. Like peer JetBlue (JBLU -3.12%)Southwest Airlines (LUV -0.54%) is beginning to add more of its own.

Starting next month, Southwest will grant access to the Transportation Security Administration's security pre-check service throughout its domestic system, the Chicago Business Journal reported last week. Elite business travelers tend to use pre-check to bypass lines and accelerate security screening.

Therein lies the benefit. Southwest already carries more domestic travelers than any other airline, and is currently in the process of expanding into Houston to take on United Continental on its home turf. Adding pre-check ups the ante further in the fight for business travelers with big needs and bigger budgets.

JetBlue, for its part, is adding not only lie-flat suites on some aircraft, but also planning next year to offer first-class cabin service on flights from New York's JFK airport to Los Angeles and San Francisco.

Who wins in all this? Business travelers, certainly. Southwest also looks to be in good position having already made significant inroads in some of the nation's largest markets for business travel. That includes my home airport: Denver International. United has a hub in Denver and, coincidentally, just reported weaker-than-expected earnings while Southwest's profits doubled in the third quarter.

But it's also early. United has come back before, and AMR and US Airways posted record profits in their most recent reports. Legacy carriers are in better shape now than they were a few years ago.

This a 15-round heavyweight battle, and the bell just rung. Do you agree? Are flying Southwest for business travel more now than in the past? Leave a comment below to let us know what you think.