GNU Octave 3.4 has just been released
gnu.org
gnu.org
First, it is a super solid platform and shows a lot of promise for the future as the build system gets ironed out.
Second, although R and Python are a lot more fashionable these days, for some good reasons and some bad, Matlab syntax is the closest thing to actual mathematics. (Some features like cell arrays and 1-based indexing may seem odd to a Algol/ Pascal/ C/ Perl/ Python/ Java programmer, it can handle any data structure with as much grace as these more "traditional" syntaxes.)
Third, Matlab has a huge share of the numeric / math world (for good reason, I think), and a plug in replacement is HUGE for us free software communist hippies.
textread() is a nice function that essentially takes an array of records (in a flat file) and turns it into a set of arrays. Basically you're performing a projection to get the set of time series you need from a time series of records.
I used to use Octave a lot instead of Matlab in grad school (computer vision) and still use it a good bit now translating/writing scripts for U-Hawaii's Oceanography program. viraptor is right, though, "ipython -pylab" is a great replacement, too
Python is where I keep going back to, for _everything_, because it has libraries for so much stuff, super-clean syntax, relatively easy integration with C, and enough extensibility.
What's particularly galling (to a matlab hater like me, anyway) is how some of the most highly-cited and useful work that's made available by researchers is done so only through matlab. The de facto standard benchmark for keypoints (http://www.robots.ox.ac.uk/~vgg/research/affine/) is a matlab function, but it's not like that code uses matlab in any interesting way, it just reads text files. And even though it's not computationally intesive (the benchmark is only on small set of images) there is a mex function involved to do the actual computation, which makes it a pain in the ass to use with octave. Basically they're using matlab as a $2000 bash shell. Same situation for the standard segmentation benchmark (http://www.eecs.berkeley.edu/Research/Projects/CS/vision/bsd...) And then there's LabelMe (http://labelme.csail.mit.edu/) the "open" annotation tool. They've got a really slick javascript UI for crowdsourcing ground truth collection for image segmentation / object classification tasks. They make the data freely available (which is awesome) but to access it you have to go through a matlab toolbox...? WTF?! I mean really, you've obviously got someone on your team who knows a thing or two about the web: take a page out of Flickr's playbook (after all they've done for the CV community) and make your data available via open standards. There's not even a goddamned download link on the page. It's like they're on the Mathworks payroll.
Grrr...
Your group might be buying single licenses or something, but pretty much all reasonably big research universities in the US have either a site license or a college/school-level license -- like maybe the whole College of Engineering or whatever.
A lot of engineers (non-CS guys) REALLY like Matlab because it's extremely easy to use with good visualizations and with all the toolboxes and stuff, you can do whatever you want. So you get a lot of ME, EE, CE, other guys saying "we want Matlab" and all of a sudden you have a good reason to get a site license.
Add to that that many computer vision researchers are really EE or applied math guys who aren't going to use some other language/tool and it boils down to free Matlab (because you have the site license) or free Octave (because it's free) and they take Matlab because it's more full-featured. Particularly, until the last few years, the plotting/visualization stuff under Octave was some mix of incomplete and very hacky. The situation has certainly become better, lately, though.
Also, as of say...2006? Matlab was considerably faster.
Also, at conferences, etc, it's easy to find books about Matlab and a salesman with a little booth who's happy to talk to you and they also advertise elsewhere a good bit.
I don't think anybody's preaching Octave, actively, except for the choir.
Edit/addendum: I think Octave is great. Just explaining why I think people choose Matlab.
Thanks for the link to LabelMe, that's cool.
This is consultancy work in geophysics. I'm writing code for a colleague to use (he does have a Matlab licence) who is working with a mining company.