I am a great fan of building bus rapid transit corridors. What this term "bus rapid transit" exactly means is not 100% clear, it is a relatively new technology (at least in its wider world embrace) and meanings haven't fully sorted themselves out. In some cities it is used to refer to roads used by express buses, or to on-street bus lanes marked separately but not otherwise segregated. In others BRT corridor means an exclusive lane - or indeed separate length of road, trench, underpass or tunnel - for exclusive bus use, or at most shared only with cyclists, pedestrians and emergency vehicles.
The key to me is the word rapid - it doesn't really matter the device so much as the the status given the passage of the bus service - traffic signal priority, frequent predictable pattern service, longer distance between stops, better bus stop facilities (mini-stations with door level platforms), real time signage as to when buses are due, top of the line vehicles. Of course a major advantage - probably the most profound - that bus rapid transit corridors can offer is that once a clear run is available for buses on a dedicated service, in peak hours (or other times as deemed necessary) the same corridor in many cases can be utilised by buses feeding off other routes to gain direct access to the central city or the key locations served. This means the fast direct (no transfers) access offered by BRT systems can extend across a whole city, in a way light rail can not. Brisbane's exclusive busways are used by 117 different routes (presumably some of these are peak hour only) and the 3.5km exclusive bus transitway being built through the heart of Winnipeg is the access corridor of 17 separate routes.
However even as a singular route in itself, with a dedicated frequent service, a bus rapid transit corridor can offer an attractive and cost effective alternative to light rail. I love public transport (as a full time bus user for at least 17 years of my life, and bus driver for 14 I have more or less lived on public transport for a sizeable portion of my life!!) but it is after all a utility - I am not sure it needs to be too damn precious, not an absurdly glamorous state of the art expression, as seems to be the wish of some light rail fans. Attractive, clean, efficient, renewable (regular vehicle/infrastructure maintenance, upgrading) that seems enough for me! Jarret Walker in his webblog Human Transit draws attention to a bus service of this nature operating near Seattle. Check out the wee propaganda u-tube - it is nothing too precious, glamorous or glorious, just good old public transport but done well. A similar system in Christchurch, where bus usage rates per capita are typically much higher than USA could probably see the same service operating at 10 minute frequencies. I would rather see about 6 or seven bus corridors of the nature here (some with added underpasses or "cut through" bus boulevards between streets etc to by pass congestion) serving all corners of the city than a single 12km glamour light rail line serving one section of the city only. During peak hours a number of express services from outer areas might also use the same corridors, but the key corridor service themself would offer fast effective access between outer areas and the CBD, university, airport and major work zones.