The chief question in most satellite radio listeners' minds has been, would XM and Sirius subscribers always remain separate? Today, the official answer has changed from "Yes" to "Sorta," with the emergence of new "best-of" selections.

In a potentially acceptable compromise with what legislators had sought prior to the merger, Sirius XM Satellite Radio announced this morning it will be making some XM channels available to Sirius subscribers as an add-on package, and that one of its Sirius radios available now can accept a la carte programming selections.

The Starmate 5 now sells for $129.99, and is available online or through Best Buy, Radio Shack, and Crutchfield outlets in the US.

Beginning today, all Sirius radio subscribers (including those with Starmate 5 models) will have access to the "Best of XM" programming option, which includes the Oprah & Friends and XM Public Radio (featuring Bob Edwards) channels, along with sports programming from the NBA, NHL, and PGA. That option adds $3.04 per month to the regular $11.95 "Family Friendly," subscription fee, which is one of Sirius' more popular packages.

For regular Sirius subscribers who pay $12.95 per month for channels that include mature content, the "Best of XM" package also features a channel called "The Virus" which, based on its description, doesn't sound all that family-friendly. That boosts the subscription fee by $4.04 per month to $16.99.

The basic "A La Carte" package lets Sirius subscribers pick and choose 50 items from a menu of standard channels at a fee starting at $6.99 per month. Certain of these channels are designated "premium" and carry an extra 25¢ monthly fee; and every premium or basic channel beyond the basics also carries the extra 25¢ fee. With this package, the two Howard Stern channels carry a much higher premium, taking the fee to $12.95 per month; at that rate, you can throw in Sirius Play-by-Play sports channels for no extra charge. The Play-by-Play option by itself boosts the fee to $11.99.

By comparison, the "A La Carte Gold" package, for $14.99 per month, boosts the number of choices to 100 items from an expanded menu, which includes both Howard Stern channels and also the "Best of XM" lineup. This includes selected XM Play-by-Play sports channels. (Fellow Hoosiers will certainly ask: XM 145, which features IndyCar racing, does not appear to be among the current "Best of XM" lineup.)

For now, the "A La Carte" and "A La Carte Gold" options are only available with the Starmate 5 model radio, which is the only one currently programmed to accept individual channel selections plus XM channels. The new setup on Sirius' online purchasing pages indicates that this may not be the case for long.

This morning, Sirius XM published a brochure for Sirius subscribers with Starmate 5 radios, explaining how they can activate these new options on their accounts (PDF available here).

All current XM subscribers, meanwhile, will have access to a new "Best of Sirius" option, which enables extra channels from the Sirius palette including Howard Stern, Martha Stewart, NFL, and NASCAR coverage. That option will boost fees by just over four bucks to $16.99 per month.

In a statement this morning, Sirius XM president of operations Jim Meyer summed up his company's marketing push: "It's hard to imagine an XM subscriber who wouldn't be interested in adding Howard Stern and NFL games, or a Sirius subscriber who wouldn't want to get Oprah's channel or follow the games of the NBA and NHL, and the world's best golfers on the PGA tour." (It would be interesting to learn how many Howard Stern listeners are regular Oprah Winfrey or Bob Edwards listeners, and vice versa.)

The point: Although this new radio isn't exactly "interoperable" by the technical definition, for many listeners' tastes, it could be close enough.

[Updates were made to the above price lists to reflect clarifications received by BetaNews this afternoon from Sirius XM.]