Do mashiach blogs prevent the geulah?

I doubt it.

I actually had a post ready, suggesting this very idea, but in jest. I was planning on pointing to the gemara in Sanhedrin 98a which reads:

אמר רבי חנינא אין בן דוד בא עד שיתבקש דג לחולה ולא ימצא

"Rabbi Chanina said: The son of David will not come until [the word of Rabbi Yekusiel] Fish is sought, for one who is sick [in anticipation of mashiach's arrival], and it is not found."

(See posts describing Rabbi Fish's prediction for next year in these posts: Part 1, Part 2, Part 3, Part 4, Part 5, Part 6, Part 7, Part 8 and Part 9.)

That is, only once Rabbi Fish stops predicting that this year, or the next year, or the year after that, will be the year mashiach finally arrives.

Geulah Perspectives refers in a blog post explaining why he is closing his blog, to a gemara which reads (on the previous amud):

ד"א עד שיתייאשו מן הגאולה שנאמר ואפס עצור ועזוב כביכול אין סומך ועוזר לישראל כי הא דר' זירא כי הוה משכח רבנן דמעסקי ביה אמר להו במטותא בעינא מנייכו לא תרחקוה דתנינא ג' באין בהיסח הדעת אלו הן משיח מציאה ועקרב 

Or, in English:

Yet another interpretation: until the redemption is despaired of, for it is written, there is none shut up or left, as — were it possible [to say so] — Israel had neither Supporter nor Helper. Even as R. Zera, who, whenever he chanced upon scholars engaged thereon [I.e., in calculating the time of the Messiah's coming], would say to them: I beg of you, do not postpone it, for it has been taught: Three come unawares:³⁰  Messiah, a found article and a scorpion.³¹

He gives it a deep kabbalistic explanation, about Keser and Daas, but it may simply be as the gemara explains it -- that only once no one is expecting mashiach, and everyone despairs of his arrival, will mashiach finally arrive. (BTW, see the discussion over at Yeranen Yaakov as to whether this is so. And see Shirat Devorah as well)

If we take it as the gemara understands it, that it will only come when people despair of mashiach coming, then perhaps the Geulah blogs are actually hastening his coming. After all, they make a prediction, and mashiach does not come. They make a prediction, and mashiach does not come. They make a prediction, and mashiach does not come. They make a prediction, and mashiach does not come. They make a prediction, and mashiach does not come. And so on and so forth. Eventually, people will give up and think mashiach is not coming at all. As the gemara in Sanhedrin says (according to some interpretations):

What is meant by 'but at the end it shall speak [we-yafeah] and not lie?' — R. Samuel b. Nahmani said in the name of R. Jonathan: Blasted be¹⁸  the bones of those who calculate the end.¹⁹  For they would say, since the predetermined time has arrived, and yet he has not come, he will never come. 

By increasing despair, the Geulah blogs may bring mashiach!

But maybe one could connect it with yet another gemara in Sanhedrin, in close proximity:

Ze'iri said in R. Hanina's name: The son of David will not come until there are no conceited men in Israel, as it is written, For then I will take away out of the midst of thee them that rejoice in thy pride:¹⁷  which is followed by, I will also leave in the midst of thee an afflicted and poor people, and they shall take refuge in the name of the Lord.¹⁸

I would suggest that many who predict the ketz imagine an importance of their own role in the happenings. Thus, to choose a random example, they believe that by dreaming of and then building a kever for Devorah HaNeviah, they are going to be the ones to bring mashiach. Or that they have the insight, where everyone erred before, in figuring out the true meaning of the Zohar, or the Gra, that year X is the ketz.

Believing that one has such a cosmic impact, either to bring mashiach, or in this instance, to prevent the coming of mashiach, it perhaps also a mark of false conceit and pride.

Hashem has a plan. And mashiach will come when he comes. Hopefully soon. What one can do is live in the present, doing mitzvos and learning Torah, as we are supposed to, and let Hashem take care of the rest. Worrying that the end is near, or being distracted by this ketz or that ketz, prevents one from living in the present.