This is the IPO filing we’ve all been waiting for: Facebook.

According to The Wall Street Journal, the hottest social media IPO of all time could be filed as early as Wednesday, and Twitter is already on fire with the gossip. It isn’t a sure thing; the Journal says that “timing is still being discussed.”

The projected valuation range is $75 billion to $100 billion, which comes in a bit lower than earlier rumors, which pegged the company at the high end.

While the race to be Facebook’s stock exchange is still said to be a dead heat, the frontrunner in the push to be Facebook’s lead investment bank is Morgan Stanley, which is edging out Goldman Sachs for the top spot in a deal where banking fees could exceed $200 million.

Facebook has already engaged The Brunswick Group to help with the IPO, the same firm that Groupon used.

Details are still sketchy, and Dan Primack of GetTheTermSheet.com has already tweeted, “WSJ now hedging a bit on that Wednesday timing for Facebook IPO.”

Here’s the rest of what is swirling about:

• According to the rumors so far, Facebook is looking to sell 10 percent of its shares, which would translate to IPO proceeds of $7.5 billion to $10 billion, based on the valuation range of $75 billion to $100 billion.
• Despite having been pitched on more exotic alternatives, Mark Zuckerberg & Co. appear to be leaning toward a conventional IPO.
• Facebook has reserved the symbol “FB” under which to trade on whichever exchange it ultimately chooses.
• Facebook will have a lot to explain to investors. Third-party forecasts called for higher 2011 revenues for the social media company, and it will have to show it can grow into a valuation of $75 billion or higher.
• The most recent private shares trading activity on SharesPost puts the stock price at $34 a share, and trading in the low $30s results in a valuation in the neighborhood of $80 billion.
• Private trading in Facebook stock has been halted, ostensibly allowing the company to compile a list of shareholders for its IPO filing.

We’re still reading the tea leaves right now: there are no definite answers on when Facebook will file for its IPO or what will be in it.

Maybe the fact that Facebook COO Sheryl Sandberg has accepted a speaking slot at Harvard Business School for May 23, 2012 is revealing—after all, she wouldn’t be able to say much during the quiet period.

Tom Johansmeyer is group marketing director of Cross Border, which publishes IR magazine, Corporate Secretary and Inside IPO.

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