I haven't written in ages and will be up front in admitting that this is going to be a short piece because I am not going to quote the people who did the hard work figuring this out but here is some pretty solid evidence that the entire "Weinergate" drama was an intentional frame job/setup.
It seems there is an exploit in Twitter/yfrog that will allow anyone to post pictures to your yfrog/twitter account without you doing it yourself. There's a full rundown at the link below. There's not much more that I can add to this but definitely read the link below.
http://cannonfire.blogspot.com/...
The short version courtesy of Sandino:
Apparently yfrog provides a user with an email address to which they can send photos which not only automatically appear in the photo gallery, but also trigger a tweet about it.
This yfrog email is not secure, and is readable in any picture URL Weiner has every sent out. The blog post linked above demonstrates clearly how this works and also shows a screengrab, which has a matching 'anomaly' of missing URL as the original hoax screengrab.
My assumption that a faked screengrab was based on hacking accounts being too difficult and dangerous for these clowns. Turns out the character assassination attempt was even easier than that.
UPDATE: See below for pics showing how the above can be done courtesy of Unit Zero
jpeg from Photobucket:

Email sent from yahoo:

Tweet Sent

Yfrog photo:

UPDATED AGAIN
A lot of people seem to be taking Weiner to task for not being able to say the picture was him or not. Now given that Weiner has said he has been hacked before maybe those doing the hacking got ahold of some photos? Or maybe he has taken photos of himself in his underwear (most likely for his wife) and given that this one doesn't appear to show a face it is not him, but he thinks it could be possible.
So far, from what I have seen, Weiner is being setup. From the fact that this Patriot person was, for all intents and purposes, stalking weiner, to the fact "he" predicted a sex scandal for weiner, to the posting of the pic as outlined above.
Does his inability to say without a doubt that the picture is not him help? Given todays media, no it does not. However the evidence points more towards a smear job than weiner doing this.
UPDATE #2 pico has a good point:
but the issue with the disappearing URL isn't quite right. In fact, if you go to the photo that allegedly doesn't have the URL, it does indeed have one. So does the one added by Unit Zero, above, despite not having one when the screencaps were taken.
So what's going on here? Maybe yfrog has a delay in stamping photos with URLs. Maybe there's a setting that posts the URL only after the owner does something (like log in, or whatever). Either way, it's not what's been explained in the diary.
Good catch, however it goes to show that there is a glitch between posting a pic via the email way and uploading one yourself. That glitch is still evident based on the screen captures.