NO! that would give Sony another reason to increase their price horribly, while the hardware for portable 500g hdd is getting cheaper as time passes by. You may also have an option to buy 2nd hand 500g hdd for much cheaper price.

320g and 500g 2.5" hdds are much cheaper now, soon 1tb will be introduced to the market. Changing PS3's hdd shouldn't be a problem at all in any models. That should solve the space problems. Unlike 360 where you need to buy M$ made hdd leaving you w/o option to shop for your desired hdd and cheaper hardware.
The only hassle would be transferring the saved contents, but hey we got a pc for doing backups.

You're being a bit harsh trhere mate, he was indeed wrong in one sense but what he meant to say I'm sure is that it costs more to buy a 20GB HDD than 60G because they're so rarely used.  Prices of HDD's drop with extra demand for them, often though like RAM the price increases as the part becomes rarely used as it's now in shorter supply or very expensive to manufacture in low volume runs. 

Haha, if I see anyone who wants to buy that, I'll tell him to get a bloody 360. That's a ripoff for $300.

A lot of folks would bite at a PS3 for $300 period. The 20gb rocks - I just wish it had wifi. As far as the 20gb drive, you can upgrade it a lot easier than trying to upgrade the 360 drive. And that alone would make a retooled PS3 with full BC back a formidable foe.

With 20 gigs you could own about 4-5 games before running out of space. If there weren't mandatory installs then it might have been a good idea.