This morning, as Apple (AAPL) shares neared $300, a Postcards reader, gslusher, weighed in on a post that Jessica Shambora, my Fortune colleague, wrote in October 2009 about the world’s largest stock-market capitalizations. Amazing to see how Apple, in less than a year, has vaulted just behind Exxon Mobil (XOM)…on its way to be THE most valuable company?

1. Exxon Mobil $329.44 billion

2. Apple $272.73 billion

3. Microsoft (MSFT) $214.87 billion

4. Wal-Mart (WMT) $196.08 billion

If one wants to be “global,” put PetroChina above Microsoft at $232.42 billion.

To think this all started with two guys building computers in a garage…