From CNN Travel Correspondent Stephanie Oswald

ATLANTA (CNN) -- Airline alliances have been the talk of the travel industry for months, but as they begin to take shape, experts are predicting that the only real benefit to consumers will be more flexibility in using frequent flyer miles.

"There's probably no winning for the consumers. There's no real cost savings in all these alliances... All the benefits are going towards these big fancy frequent flyer programs," said Randy Petersen of InsideFlyer Magazine.

Continental and Northwest airlines were the first to team up in January. That was followed by an alliance between US Airways and American Airlines. A union between Delta and United kicked off on September 1.

"Most of the alliance activity domestically has to do with frequent flyer programs, in order to give the frequent flyer a bigger network, more opportunities to earn miles (and) more opportunities to earn free trips," said Bob Booth of Aviation Management Services.

The alliance between Delta and United allows travelers flying domestic routes on one of the airlines to credit their frequent flyer miles to either carrier.

Delta and United are not allowing miles to be pooled for award ticket redemption. However, the US Airways-American alliance does allow flyers to use miles from both accounts to get a free ticket.

For example, a passenger could combine 11,000 American miles with 14,000 US Airways miles to get a free ticket to fly either airline. (Flyers must use at least 1,000 miles from each account.)

Some of the airline alliances will give passengers access to each carrier's international routes, which could be the biggest boon for flyers.

Skeptics say the added options provided by the airline alliances won't actually make much difference to consumers because air traffic is so heavy these days that it would be difficult to secure a free flight.

The bottom line is that each airline alliance is different, so flyers should check with the airline before making arrangements.