SanDisk has introduced its 4GB microSD High Capacity flash memory card, making it the highest capacity yet in the world's smallest flash memory card.  This enables users to store up to 1,000 songs (based on 4 minutes of 128kbps audio), up to 8 hours of MPEG4 video at ~1Mbps or up to several thousand photos. 

Mobile phones that use microSD will need to have their firmware upgraded to support this card, however, the equipment needs to support the SD HC standard in order to handle cards of 4GB or higher.  This card has an SD Speed Class 2 rating, which means that the card supports a minimum sustained write speed of 2MB/sec. 

It is interesting to see how much can be crammed into such a small space.  For example, this card can hold close to a single layer DVD's worth or almost 6 CDs worth of data.   While this density could potentially allow several hundred Gigabytes to fit in the physical space of a 1.8" or a 2.5" hard drive, unfortunately the cost of flash memory is still far too expensive for this to be worthwhile.