although i havent updated the thread yet, i do have openstep running on the macbook 2.0. performance is pretty good and i do feel the machine is quite capable. the current adobe apps do run slow under rosetta though, so you may be disappointed there if you use them. it is an excellent value which is hard to dispute. i wouldn't hesitate to recommend one. where i have found a few minor issues is with the design of the machine itself.
though its the smallest machine currently in the apple line, i still think its too big to fit my definition of portable. unfortunately, there aren't any other options. the 15" powerbook is even bigger. the rectangular wide aspect screen is nice for some things, but to me isnt worth the size and weight trade off. especailly with a max internal resolution of only 1280 x 800. at the same time though, all of my remote needs are covered by a 12" powerbook. (i'm sure many would just consider that too small. if i need a bigger screen, i just use an external display.)
the keyboard design can be limiting in some ways, too. i'm currently using the black model and it is hard to see in dim light. (no back lit models are available in the macbook line.) if you are in any type of non standard position, which i frequently am while reading web news and lying on the sofa, it can be annoying. also, the front edge of the machine, where youd rest your wrists while typing, was notably sharp when it arrived. it was uncomfortable enough that i ended up pulling out a scraper and several grades of sandpaper to round it off for a feel similar to what i'm used to with the powerbooks.
beyond that, i honestly dont have anything to complain about. depending on how portable you need to be, waiting until january for the possible anouncement of an apple ultra light might be worth considering. but for a mostly stationary machine that will occasionally go on the road, it's very hard to beat.
as for the unix aspect, os x has its own subtle flavor.
eta. matlab just announced a beta for intel macs.
www.mathworks.com/support/faq/macintel.html