Many business schools established new online programs following the requests of their professionally-active students who want to attend lectures and seminars while working. The course content, accreditation, contact with the faculty and, implicitly, the overall reputation of the program stays the same. You can also compare 'traditional' and online MBAs based on their admission criteria and the competitiveness level and notice they are quite similar. Maybe because they are fairly new in comparison to the on-campus MBA tracks, it's not so easy to pinpoint them on the 'virtual mindmap' of the general public. However, specialized publications such as The Financial Times or The Economist talk about the online MBAs as of 'the next big thing' in terms of business administration studies.
You can read here the latest online MBA programs rankings by The Financial Times and get an idea about where your prospective online MBA stands. You can also use the comparison function in the SearchMBA results list.