I just came up with a new theory for what the symbol means;

it’s future Hiro’s call sign.

Think about it, it’s practically following the Heroes around, and it most likely would have originated off of Hiro’s sword, with it meaning godsend/great talent. Godsend + great talent? sounds pretty superhero-esque to me, what a better symbol for Hiro, especially with a name like that?
The reason it has been in all the Hero’s lives, is because Hiro has been “nudging” all the Heroes together by influencing reality bit by bit, stopping time and moving this it over here, that bit over there, so that things go “right” (aka, no bomb). He’s been orchestrating the whole thing, and as a call sign he’s using the combined symbols for godsend and great talent. And it would help to have another hero in AWI, so he teamed up with the Haitian. That’s why the Haitian has the symbol on a necklace, and why he defected from AWI.
It also makes sense that the one thing he would actually talk to someone about (and risk creating a rift for) would be to save Claire. If Peter hadn’t heard “save the cheerleader”, he wouldn’t have gone to save her and wouldn’t have absorbed her healing powers (which is how he survived falling onto the taxi, and will live through his fight w/ Sylar), she would have died and Mr. Bennet would have continued working for AWI (rather than against like he is now). Hiro would have gone straight to New York without meeting Charlie, and would never have met Nathan in person, most likely wouldn’t have actually met Issac, and wouldn’t have known to get the sword. It also would have helped to have the Partner of Claire’s dad as an ally, so he could guide her, not erase her memory when he was told to, and try to hide her.

Linderman is still a bit of a puzzle though, (seriously though, pot pie? awesome. the only thing that could have made that better is if he was making waffles) he could be also working for Future Hiro, especially since he seems to be collecting a whole bunch of stuff about the Heroes before they even know it’s important to them (The sword, the missing painting), and making sure he has connections to them (Nathan’s campaign, Jessica’s money issues). He might just have precognition as a power though (which would explain how he got all his money in Vegas).

Okay, i just needed to drain my brain.

Zettageek

Edit: YAY! Hiro is posting on his blog again! http://blog.nbc.com/hiro_blog/2007/03/bound_by_death_and_luck.php

Wait…

rereads

*gasp* it’s future Hiro!

How would one find a flower

Hitohana is Japanese for flower. He’s trying to contact Hana!
…

When will I be free? When will we be free? Fates timed to precision. We follow a path. It crosses with each other.

I knew it! he’s trying to fix the past, but he’s tired of it, and wants to get on with life! Fates timed to precision! Ha! Yes!

Find me. Reach me. Email time@primatechpaper.com.

My search continues for petals. The flower that drops no trace. A flower. Open your eyes so we can talk. Communication is conductor of truth.

Petal is Hana in Japanese, he’s definitely trying to contact Hana, and if you mail that address, you get “Who are you? You’re not a truth seeker. Go away.” most likely because you AREN’T Hana.

At the end there are ultimately many futures. At the beginning primarily, there is only one departure. History is delicate. It begins with one. Many butterflies cause too much chaos.

He’s talking about the butterfly theory, a single butterfly flapping it’s wings differently can cause massive changes in the future. Too many can be hard to control, even with time travel. He might be having trouble getting everything working right.

One flap, precise catalyst. To see light again, a rift will be chanced. I grow weary of hiding on the 15.

He is going to try to change one thing to change it all. A rift will be chanced, could mean going to see Peter on the subway, especially if hiding on the 15 means hiding on the subway train. “15″ could also mean floor 15 of the Deveaux building (unlikely as most of the plot issues at the Deveaux building were on the roof), or it could be the floor/apartment number of Issac’s apartment (never mind: Issac is in apartment 7 but at 215 Reed St).

The irony. Once drowned within homogeneity, yearned to be special. Found air to drown myself bearing a mark. To a flower I speak. May I reach you to end this insanity. Preach the truth. Open the minds. There are no monsters. Only visions that are placed within minds.

They used to all be the same, wanting to be unique (this could also be a reference to Sylar). Bearing a mark could be the symbol. To a flower I speak. May I reach you to end this insanity. More references to attempts to contact Hana. There are no monsters? Hmmm… Sylar could end up being non-evil? maybe he steals Issac’s brain, paints the future, and because he can see how things work, realizes he caused the bomb and feels guilty. That could fit with “Visions placed within minds”

The stardate 3000.0 thing could also point to it being from future Hiro, because the other posts were all stardate 17XX.