By web2.0 do you mean elgg, jcow and other low quality platforms?
No such thing as a low quality platform.
A PR5 link is a PR5 link
Their are a lot of low quality sites on Elgg for sure...so don't use them. But the idea that Elgg itself is somehow ingerently "low quality" is a twattish thing to say.
I've got some D0follow high PR Elgg sites on my list (there arwe d0follow Ellg - just like there are D0follow WIKI if you know where to find them)
Do you think Google goes.
Great content..Check
Images and multimedia...Check
High PR authority....Check
Relevant outbound link and anchor text...CHeck
CMS.... Oh SHIT.. The idiot's used Elgg as his CMS!!..Scratch that it's all crap!! Wonder why we made it PR5 in the first place? Are WE feeling stupid now!?
That doesn't happen - at all - ever - for any platform.
Blogs, forums sigs, all CMS platforms.
Good ones are good - bad ones are bad.
Too many of the same type is not good.
That's probably why noobs think forums and blogs are bad becasue of those ass-hurt idiots who got penalized for having 99% of their links created in 40 minutes with a "scrapebox blast" or a "Xrumer forum spam" blast.
Clues in the title numb nuts..If it says "Blast" and you are pointing it to your site..it's probably CRAP.
I get fantastic power from forums, blogs, WIKI's article sites and open source WEB2.0 CMS.
If I just scraped 5000 Elgg sites (90% of which are indeed very low authority) and pressed "Blast" I would get shit results.
If I found 15 of them with real authority, some d0follow, PR between 2 and 6, added some from other platforms (JCOW you mention - fine - same rules apply) end up with say 50-60 high PR authority. Sprinkle in some custom coded sites (Tumblr, Blogger, Wordpress etc) I've got a really powerful setup.
You mix them up, choose mostly only the good ones. Add custom sites to the mix.
Another rule here. if it's "Auto Approve" it's probably a spam filled low authority douche bag of a site.. and if it isn't when you post on it..it will be some day. What sort of numb nuts webmaster leaves his site open to publish spam and outbound links for other people with no control?
This idea that a platform is "low quality" is noobish nonsense.