There are two companies with “draft 802.11g” chipsets already out of the gate — Broadcom with their 54g chipset, and Intersil with their Prism GT chipset. These chipsets are what other companies use to make their 802.11g hardware.
Apple uses the Broadcom chipset for AirPort Extreme system (access points and client hardware), as does Belkin for their 54g Wireless system, Buffalo Technology for their AirStation G54 system, and Linksys for their Instant Wireless-G system. D-Link uses the Intersil chipset for their AirPlus Xtreme G (named after watching Steve Jobs’ Macworld keynote?) system, as does Netgear for their forthcoming system.
These almost-802.11g products are pretty interesting. They’re several times faster than 802.11b. Pricing is extremely reasonable, with access points (with the exception of Apple) selling for south of $150. (I personally refuse to buy an AirPort Extreme access point, not only because of the price, but also because Apple refused to replace my AirPort when it died an early death because of their design problem.)
Should you upgrade to 802.11g? No — at least not yet. The 802.11g standard isn’t even final yet. Interoperability between different vendors isn’t there. Even more worrisome, interoperability with 802.11b is poor. Wait until 802.11g is ratified this summer, at least — by then the chipset vendors will have had a chance to shake out the bugs in their firmware.