Okay. Once upon a time I might have been considered a quasi-expert on this topic, so I'll give it a shot.
1. Most people's anecdotal evidence claiming that something's wrong with the online shuffles comes from a statistically insignificant sample and therefore useless. There are a gazillion people with ginormous online hand histories, and AFAIK they haven't discovered any actual anomalies.
2. Computers cannot generate random numbers. Instead, they rely on "pseudo-random" algorithms to generate sequences which, mathematically, mimic a random sequence. A few years ago there actually was an online poker room that used a very simple pseudo-random number generator (on top of a bad shuffling algorithm), and an exploit was found by some programmers. Here's a link:
http://www.developer.com/tech/articl...3_616221_1?o=0
These days, most sites use much more sophisticated generators, and add entropy via real-world events (e.g., temperature, network traffic, etc.). Often, these algorithms are audited by a third party. Assuming these algorithms work the way they say they do, it's about as random as you'll ever get, and certainly more random than a few riffs by a live dealer.
3. My guess is that if any exploits exist in current online poker software, it is probably not related to the random number generation per se. It is nearly impossible to "guess" the sequence in the same manner as discusssed in the article. I also think it's highly unlikely that any sites would purposely "rig" their software, and arguments along the lines of "well, why *wouldn't* they?" are not credible.
4. That said, anyone who thinks online poker sites are non-exploitable is being naive. In any networked client-server environment, you have a bunch of machines with buggy hardware running undoubtedly buggy server software on buggy operating systems, communicating *over the internet* to buggy client software running on buggy operating systems on buggy hardware being used by users with buggy brains. It's a hacker's paradise. The best programmers in the world can't create a completely secure *web browser*. The odds that online poker software is completely secure is zero.