CLAMP's latest series is Tsubasa Reservoir Chronicles, and for those of you who don't know, Arashi and Sorata make a cameo appearances!

In the series, Shaoran (of CCSakura), Fye (new character, and Kurogane (new character) are lead throughout different worlds by Mokona (of MKR) in search of Sakura's memories. They were scattered when someone tried to take her soul from her (apparently she holds some mysterious and awesome power.) They appeal to Yuuko (of XXXHolic) for help, who gives them Mokona.

Hanshin Republic
The first world they awaken in is the Republic of Hanshin, as luck would have it, in Arashi & Sorata's lodging house! CLAMP threw us fans a bone, and in this universe Arashi & Sorata are living quite happily together, married. They don't say much about themselves except that they had to give up something to Yuuko in exchange for their being together, and that Arashi was some sort of sorceress earlier. Sora is a history teacher as a day job.

Piffle Country
Arashi makes a brief appearance as a snapshot Sorata presumably uses as a good luck charm in the Piffle Princess Race. This image is from shortly before the preliminary race.

Arashi and Sorata return again as members of the Tower gang in this post-apocalypse X Japan. Arashi is revealed to have a sense for magic powers as in this world she was also a miko.