This is absolutely not true. First of all, the N810's internal memory card is formatted with JFFS, which is optimized for flash media. But even if this were not the case (i.e. with FAT-formatted external memory cards), all modern memory cards implement wear leveling at the hardware level, regardless of the driver that is used. Even under intense usage, it would take many, many years to wear out even the cheapest memory card.

A class 6 SDHC card can write at 6 MB/sec. On a 4GB memory card, it would take 683 seconds to write to every block of a 4GB card exactly once. (Due to wear leveling, this occurs whether you're writing a 4GB file once or rewriting to the same 4-byte file a billion times.) Even the cheapest memory cards have blocks with a lifetime of at least 500,000 writes. If you were constantly writing data (without reading it), it would take 500,000 * 683 seconds (almost 11 years) for the memory card to fail.

Most people aren't constantly writing to their memory cards. And most memory cards support more than 500,000 writes per block. Flash memory is more likely to fail for other reasons before it fails for being written too much.