webOS 1.x came with an emulator that was allowing you to run old PalmOS applications within the webOS framework. With the release of webOS 2, HP decided to get rid of this emulator but thanks arthurthornton @ PreCentral it is now possible to bring it back. This method uses files from both webOS 1.4.5 and webOS 2.0.1 to enable the classic PalmOS emulator.
All the credits go to arthurthornton, consider a donation to him if it helped (link in PreCentral forum).
You can follow those steps to install the PalmOS classic emulator in your webOS 2 device [from How to Keep Classic with webOS 2.0 and above]:
1) Download the attached ZIP; Extract it; Open the "files" folder; (STAY in this folder in ONE WINDOW, open new file browsing window)
2) Download the Pre/Pre+ 1.4.5 webOS Doctor
3) Download the Pre2 2.0.1 webOS Doctor
4) Extract the doctors as follows:
1.4.5: Unzip the Doctor file (.jar); Open "resources" folder; Untar webOS.tar; Open "webOS" folder; Untar "nova-cust-image-castle.rootfs.tar.gz"; Open "nova-cust-image-castle.rootfs" folder (STAY in this folder, open new file browsing window)
2.0.1: Unzip the Doctor file (.jar); Open "resources" folder; Untar webOS.tar; Open "webOS" folder; Untar "nova-cust-image-roadrunner.rootfs.tar.gz"; Open "nova-cust-image-roadrunner.rootfs" folder (STAY in this folder)
5) Pull the following file out of the webOS 1.4.5 doctor: /usr/lib/palmos/rom0/ROM.bin
6) Pull the following FILES out of the webOS 2.0.1 doctor:
/usr/bin/PalmClassic
/usr/lib/BrowserPlugins/MAPartsAdapter.so
/usr/lib/libMA_Blazer.so
/usr/lib/libMA_Cap.so
/usr/lib/libMA_Emul68kStub.so
/usr/lib/libMA_HostControl.so
/usr/lib/libMA_HsExtensionsShim.so
/usr/lib/libMA_HsNavShim.so
/usr/lib/libMA_PalmosLinuxDal.so
/usr/lib/libMA_PartsLib.so
/usr/lib/libMA_PartsSerialDriver.so
/usr/lib/libMA_Phone.so
/usr/lib/libMA_PhoneInterfaceLib.so
/usr/lib/libMA_PmBtPartsUi.so
/usr/lib/libMA_PmConnectionManagerLib.so
/usr/lib/libMA_PmConnectionManagerPalmOsLib.so
/usr/lib/libMA_PmFakeSlotDriver.so
/usr/lib/libMA_PmLinuxFs.so
/usr/lib/libMA_PmLinuxUtils.so
/usr/lib/libMA_PmMaWelcome.so
/usr/lib/libMA_PmNetPrefLx.so
/usr/lib/libMA_PmNetSim.so
/usr/lib/libMA_PmPCBtLib.so
/usr/lib/libMA_PmPartsNotifyLib.so
/usr/lib/libMA_PmPdnsLib.so
/usr/lib/libMA_PmRomTokenLib.so
/usr/lib/libMA_PmSystem.so
/usr/lib/libMA_System.so
/usr/lib/libMA_TelephonyInterfaceLayer.so
/usr/lib/libMA_Ui.so
/usr/lib/palmos/.copyclassicapps.sh
/usr/lib/palmos/.preferences-default
/usr/lib/palmos/.prepare.sh
/usr/lib/palmos/.uprepare.sh
/usr/lib/palmos/Read Me.txt
/usr/lib/palmos/classic.rgba
/usr/lib/palmos/expired.rgba
/usr/share/dbus-1/system-services/com.motionapps.palmos.service
/usr/share/ls2/roles/prv/com.motionapps.palmos.json
7) Copy those files into the "files" folder referenced in STEP 1
8) Download IPK Packager (Ipk Packager.jar - ipk-packager - Ipk Packager v1.6 - Project Hosting on Google Code), a product of Jason Robitaille
9) Open IPK Packager, browse to the "files" folder referenced in STEP 1
10) Package it up, install through WebOS Quick Install (DO NOT USE the webOS SDK)
If it doesn't work: REMEMBER your directory structure. Make sure the above copied files are exactly where they should be (i.e. ROM.bin needs to be in files/usr/lib/palmos/rom0)
You can see the PalmOS Classic emulator in action on a webOS 1.x device in the following YouTube video:

You can get more information @ How to Keep Classic with webOS 2.0 and above
Don't forget to follow us on Twitter and join our Facebook Fan page to stay updated.