32-bits give you 4Gb
While the main contents of the article aren't too wrong, I just have to point out that 32 bits of addressing gives you a 4Gb addressing space. (Unless of course you use signed pointers, in which case you'd have to point out where you keep the negative memory.)
Also, most current 32-bit processors can already support more than 32-bits addressing. (For example G4 PowerPCs and pentiums since P3 support at least 36-bits physical addressing.) Of course, using 32-bits in usercode it's impossible for a single task to access more than 4Gb.
The article also failed to mention the end of the epoch in 2038, when 32-bit signed unix-style time will rollover.