I must change my opinion as the IBM machine that runs Lotus keeps changing its stategy and the name of the product.
The new product is WebSphere Everyplace. It is still in beta and is the next generation of "Everyplace"
mNotes does offer a wireless enterprize solution now too that as long as you are connected to the network somehow, it will sync.
In fact I got a promo email about it just last week trying to convice me that it was better than the blackberry solution. (Blackberry is a separate device yet with a dedicated server. Blackberry OS is a Java VM machine and their webbrowser is even worse as it doesn't support any jscript at all)
So, do mNotes -
http://www.commontime.com it is the best solution out there (Oh and they provided the wireless connectivity at LotusSphere this past year.)