My iPad 1 is jailbroken as well for multitasking gestures, retinapad, sbsettings, the pandora skip hack, and MyWi mostly (mywi's paying dividends right now because AT&T's lovely dsl is down at the moment, ugh). I use the gestures a lot to warrant the jailbreak, sbsettings is still an amazing hack, and MyWi definitely comes in handy for situations like this, simply because I cannot justify both giving up my unlimited plan and paying $15 extra for the rare exceptions I would tether, so jailbreaking is great for me.
Jailbreaking will still have some advantages going forward even with iOS 5 since Apple haven't implemented a quick switch for settings; optimized iPhone apps for iPad in terms of resolution; may not put multitasking gestures in for iPad 1; and doesn't allow me to tether every now and then without changing my entire iPhone data plan. Those are my justifications for it...