MacRumors notes that Apple has recently updated a knowledge base support document offering solutions to Wi-Fi issues that a small minority of iPad users have been experiencing. Shortly after launch, Apple's support forums were rife with posts about poor Wi-Fi throughput and lost connections on the iPad. Despite the apparent flood of complaints, Apple has maintained that only a "very small number" of iPad users are affected with Wi-Fi issues (which makes sense because, even if there are 5000 posts from users reporting Wi-Fi connection issues, that's a far cry from the one million iPad's Apple has sold).
For the unfortunate few who are experiencing iPad Wi-Fi issues, there's good news: the recently updated support document states that Apple is hard at work on a fix and will "address remaining Wi-Fi connectivity issues with a future iPad software update." Until then, the support document lists a number of workarounds including updating your Wi-Fi router firmware, adjusting the iPad's screen brightness, renewing your IP address, and using WPA or WPA2 wireless security.