The only hotel that's part of a chain/reward program right now is the Novotel. I haven't heard of any changes on the horizon. The Milles Collines got bought by a Congolese company and will get refurbished, but I've heard nothing about joining any chains.

There is a convention center and hotel project near the airport (across from the central postal facility on the first main traffic circle on the way into town, for those of you who know the city) that will supposedly have a high end hotel, but the developers have told me they don't have any lead on operators yet.